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Horizon scanning to identify invasion risk of ornamental plants marketed in Spain
expand article infoÁlvaro Bayón, Montserrat Vilà
‡ Estación Biológica de Doñana, Sevilla, Spain
Open Access

Abstract

Horticulture is one of the main pathways of deliberate introduction of non-native plants, some of which might become invasive. Of the 914 commercial ornamental outdoor plant species sold in Spain, 700 (77%) are non-native (archaeophytes excluded) marketed species. We classified these into six different lists based on their invasion status in Spain and elsewhere, their climatic suitability in Spain and their potential environmental and socioeconomic impacts. We found sufficient information for 270 species. We provide a Priority List of eight regulated invasive species that were still available on the market. We also established an Attention List with 68 non-regulated invasive and potentially invasive species that might cause various impacts. To prioritise the species within the Attention List, we further assessed the risk of invasion of these species by using an adaptation of the Australian WRA protocol and the level of societal interest estimated from values of the Google Trends tool. We also propose a Green List of seven species with probably no potential to become invasive, a Watch List with 27 potentially invasive species with few potential impacts and an Uncertainty List with 161 species of known status but with insufficient information to include them in any of the previous lists. We did not find sufficient information for 430 (61%) of the marketed non-native plant species, which were compiled into a Data Deficient List. Our findings of prohibited species for sale highlight the need for stronger enforcement of the regulations on invasive plant species in Spain. In addition, our results highlight the need for additional information on potential impacts and climate suitability of horticultural plants being sold in Spain, as insufficient information could be found to assess the invasion risk for most species.

Keywords

e-commerce, Google trends, horizon-scanning, impact assessment, non-native plants, nursery, priority list, risk assessment

Introduction

The introduction of invasive non-native species by humans may be accidental – for example seed crops as contaminants amongst cargo – or deliberate (Mack et al. 2000), such as the introduction of species used in forestry, aquaculture and horticulture. In particular, the sale of ornamental plants, including sale by nurseries, is the main deliberate pathway for plant invasions (Van Kleunen et al. 2018) which includes some of the most harmful invasive plant species in the wild (Hulme 2007).

There is a close relationship between domestic market-based propagule pressure and invasion success (Dehnen-Schmutz et al. 2007a; Johnston et al. 2009; Blackburn et al. 2013; García-Díaz et al. 2015). Horticulture activities reduce biotic and abiotic stresses on plants, bring species of different geographic origin together and increase the likelihood that plants escape into the wild (Niinemets and Peñuelas 2008). Moreover, introduction biases, or preferences for non-native species that perform better than natives (Chrobock et al. 2011), include plants that have increased germination rates, faster and larger growth and higher fecundity than native plants (Chrobock et al. 2011; Parker et al. 2013; Maurel et al. 2016). Therefore, the commercial use of non-native ornamental plant species is not only important as the main pathway of introduction (Hulme 2007), but it also favours the invasion potential of these plants and their impacts. In fact, in less than 20 years on the market, some non-native species can become invasive (Pemberton and Liu 2009).

The most effective way to manage the impacts of non-native species is through prevention (Convention on Biological Diversity 2010). In the last two decades, there has been great progress in developing risk assessment protocols as an essential management component to identify potentially invasive species (Pheloung et al. 1999; Leung et al. 2012; Roy et al. 2014, 2015). Most of these risk assessments are used to rank non-native species according to their probability of becoming established and causing harm. Horizon-scanning of invasive species is a particular type of rapid screening risk analysis based on the systematic examination of future potential threats, leading to the prioritisation of non-native species for further investigation (Roy et al. 2014). Horizon-scanning has been applied when prioritisation identifies a small fraction of species selected from a large list of scanned species, for which a thorough risk analysis is not feasible in a short period of time (Andreu and Vilà 2010; Roy et al. 2015; Roy et al. 2019). This is the case, for example, for testing the invasion risk of all ornamental plants commercialised within a country because the number of non-native plant taxa sold is very high.

A parsimonious way to perform a horizon-scanning analysis for ornamental plants is to use four of the most widely used criteria to identify potentially invasive species: climate matching, being invasive elsewhere, their potential impacts on the environment and their impacts on socioeconomic activities (Weber and Gut 2004; Otfinowski et al. 2007, Gassó et al. 2010; Blackburn et al. 2014; Roy et al. 2014).

As the number of non-native species being used as ornamentals is very high, but resources are limited to manage them all in the same way, it is necessary to create prioritisation lists of plant species identifying those that are (1) regulated invasive but still commercialised, (2) potentially invasive with the risk of causing numerous impacts, (3) potentially invasive with few potential impacts, (4) probably safe because there is no potential to establish in the wild and (5) those for which there is insufficient information to classify them by their risk of invasion and impact (Dehnen-Schmutz 2011). This coarse screening is the basis for prioritising the potentially most invasive species and to later perform a more detailed risk assessment (Pheloung et al. 1999; Weber and Gut 2004; Andreu and Vilà 2010; Gassó et al. 2010), as well as for proposing a list of the least harmful species (Gederas et al. 2012).

Since many regulations expressly prohibit the commercialisation of listed species, it is expected that none of them is sold. However, regulation is not always effective, especially for the online plant trade (Humair et al. 2015). In fact, many nurseries continue to stock and supply invasive regulated species (Wirth et al. 2004; Cronin et al. 2017). In addition, nowadays most of the nurseries offer internet purchasing. This model of commerce is currently one of the most important sources of gardening plants (Humair et al. 2015). The online plant trade significantly increases transportation distance and propagule pressure of non-native species (Walters et al. 2006; Lenda et al. 2014; Humair et al. 2015). As an innovative approach, the Google Trends tool can be used to forecast consumption and commerce, which is a valuable source of information (Vosen and Schmidt 2011). Therefore, the level of interest in each ornamental species measured by Google Trends can provide information on the interest for a particular species by society in general. Google Trends provides information on how frequently a keyword or group of keywords has been searched for on the Internet. Resulting data are not necessarily composed of only people interested in buying the plant. In fact, it is possible that some of these searches are performed because they are looking for ways to control or manage already invasive species. In our study, we used Google Trends data to assess "popularity" or "interest", defined in a broad sense, as the data do not allow distinguishing whether plant name searches were motivated by Internet users’ positive or negative views of a plant.

To our knowledge, this tool has not yet been used for the prevention of biological invasions.

In this paper, we perform a horizon-scanning analysis of the 914 commercial ornamental outdoor plant species in Spain from a total of 1063 taxa to facilitate policy implementation. The main aim is to generate six species lists based on their regulation and invasive status in Spain and elsewhere, climate matching between their native region and Spain, the magnitude of the environmental and socioeconomic impacts they might cause and their societal interest (Fig. 1):

Figure 1.

Flow diagram of horizon-scanning of commercial ornamental non-native plant species in Spain and their classification into respective lists. Colour codes correspond to those in Table 1.

• A Priority List that includes regulated (by Spain or the EU) invasive non-native species that were still commercially available in the Spanish peninsular territory (Spain, hereafter).

• An Attention List that includes climatically suitable non-regulated invasive in Spain and potentially invasive species (i.e. invasive elsewhere) with many potential impacts.

• A Watch List that includes climatically suitable non-regulated invasive in Spain and potentially invasive species (i.e. invasive elsewhere) with few potential impacts.

• A Green List that includes species with no climatic suitability and probably no potential to be invasive in Spain.

• An Uncertainty List that includes non-invasive species with probably no potential to be invasive that do not meet the requirements to be included in the Green List. It also includes species with known invasion status but with insufficient information available on impacts and non-native species with known invasion status but with insufficient information on climatic suitability or invasiveness elsewhere.

• A Data Deficient List with all the non-native species with no information about their invasion status and not enough data to classify them in any other list.

To rank the species of the Attention List, we conducted an in-depth analysis based on their risk of invasion and societal interest. The risk of invasion was scored according to the Australian weed risk assessment performed by Pheloung et al. (WRA 1999). This WRA protocol has been tested successfully for its consistent accuracy in different geographic regions (Gordon et al. 2008) including Spain (Gassó et al. 2010). Societal interest in non-native species was measured using Google Trends. We wanted to answer the following questions: Does the risk of invasion and interest to society grow across the different invasion status groups of species currently in Spain (i.e. not in the wild, casual, naturalised and invasive)? Does the number of potential environmental and socioeconomic impacts rise with increasing invasion status. Moreover, for each non-native species, we calculated a Priority Index based on the impacts, WRA score and interest of the species. We tested if the Priority Index increased with increasing invasion status of the species.

Material and methods

We compiled a database including the vast majority of ornamental outdoor plants with commercial use in gardening in the Spanish peninsular territory excluding the Canary and Balearic Islands (Spain, hereafter). We also included indoor plants that can survive and/or reproduce outdoors. However, we excluded strictly indoor plants because their ecological requirements might prevent survival outdoors. We included fruit trees as they are of ornamental use in public and private gardens and green areas, but we excluded vegetables used in horticulture. The list of taxa was compiled through the systematic consultation of catalogues from the 21 main Spanish nurseries (Appendix 1) between December 2015 and October 2016, which provide plants for sale across the country. The number of new taxa added to the database (Appendix 1) did not increase at all after the 15th nursery catalogue was consulted. The total number of taxa compiled was 1036, of which 914 were actual species. Hybrids or genus level taxa were not included in the analysis and infraspecific taxa were pooled into species.

According to their origin, we first discriminated between native species and non-native species in Spain. We then identified archaeophytes (i.e. species introduced before 1500 A.D.), following Pyšek et al. (2004). Archaeophytes were not included in the analysis because they are poorly recorded and, for many species, their non-native status is under discussion.

Species were further classified according to their invasion status in Spain, following the definitions recommended by Richardson et al. (2000): not in the wild, casual, established or naturalised (hereafter "naturalised"), invasive non-regulated in Spain or Europe (hereafter "invasive") or invasive regulated in Spain or Europe (hereafter "regulated"). Invasion status in Spain, as not in the wild, casual, naturalised or invasive, was based on the information provided in the Spanish Atlas of Invasive Non-native Plants (Sanz Elorza et al. 2004). The regulation status of the species, that in Spain involves the ban of possession, transport and commerce of living beings and propagules, was based on the Spanish Catalogue of Non-native Invasive Species (BOE 2013) and the List of Invasive Alien Species of Union Concern (European Commission 2016, 2017).

Once the non-native species were classified into these five invasion status groups (i.e. regulated invasive, invasive, naturalised, casual, not in the wild), we proceeded to perform the horizon-scanning to classify the species into the respective lists based on the flow diagram illustrated in Fig. 1 as follows:

All Regulated species were directly included in the Priority List, whereas invasive species were considered for impact assessment (see method below).

Naturalised species were identified as invasive elsewhere, based on the CABI Datasheets (2018) and the Global Invasive Species Database (Invasive Species Specialist Group 2015). Naturalised species that are invasive elsewhere were regarded as potentially invasive species and were considered for impact assessment. Naturalised species not invasive elsewhere were included in the Uncertainty List.

Casual and not in the wild species were screened for climatic suitability in Spain (see method below). For species climatically suitable somewhere in the country, with a medium to high level of confidence in the likelihood, we checked whether they were invasive elsewhere (Roy et al. 2014). Species that were not climatically suitable and not registered as invasive elsewhere, were included in the Green List (Dehnen-Schmutz 2011), commonly known as the "white list" by decision-makers. In contrast, species that were climatically suitable and were invasive elsewhere were regarded as potentially invasive species and thus considered for impact assessment. On the other hand, species that were climatically suitable but not invasive elsewhere and species that were invasive elsewhere but not climatically suitable were included in the Uncertainty List.

Finally, all the species naturalised or casual in Spain, for which we could not find sufficient data about being invasive elsewhere and those for which we have a low level of confidence in the likelihood of climatic suitability or no data at all, were included in the Uncertainty List. This list also includes species not in the wild that are invasive elsewhere rather than Spain, species that are not climatic suitable or species in which the level of confidence in the likelihood of climatic suitability is very low.

In contrast, the Data deficient list includes species not in the wild, with no data on status elsewhere and on climate suitability.

Climatic suitability

The climate in Spain is a mosaic of three main climates: Oceanic in the NW, Mediterranean continental in the centre and Mediterranean maritime in the E and S of the country including semi-arid areas (Ninyerola et al. 2005). Furthermore, Spain is a mountainous country, in which elevations over 1500 m a.s.l. are common and the highest peak rises to 3480 m a.s.l. Mountainous areas impose sharp topographical-climatic gradients where these three climatic types gradually change to a Mountain climate, characterised by cold, strong winds and abundant rainfall or snowfall. We know from previous regional analyses that the establishment of non-native species is enhanced in mesic conditions (i.e. intermediate temperature and moisture levels), such as those close to coastal areas (Gassó et al. 2009, González-Moreno et al. 2014).

Precipitation was not considered as a criterion for climatic suitability because Spain has a wide rainfall range. Since our analysis is not spatially explicit, at the regional scale, there are suitable conditions for non-native species to establish and spread (González-Moreno et al. 2014). According to AEMET (2016), the town with the highest rainfall is Vigo (NW Spain), with an average of 1790 mm per year. The climatic station registering the lowest amount is Almería (SE Spain), with an average of 200 mm per year. Therefore, due to this wide range of rainfall in our study area, we did not consider tolerance to drought or waterlogging as climatic classification criteria for the risk of invasion at the country scale.

To follow the precautionary principle, our criteria on temperature suitability were based on the highest absolute minimum and the highest mean of the minimum in the coldest month. This implies that there are many territories in Spain that, having lower minimum temperatures than the threshold chosen, will be less susceptible to invasion by the species of concern. In this way, we minimise the false negatives that may arise. Thus, we considered a plant to have climatic suitability to survive in Spain if it met two temperature criteria: (1) it can tolerate temperatures below the highest historical absolute minimum temperature in Spain, which was 0.2 °C in Almería (9 February 1935); and (2) it can tolerate temperatures below the highest mean minimum temperature in the coldest month in Spain, which in Tarifa is January at 10.8 °C (mean recorded from data between 1981 to 2010) (AEMET 2016). The air temperature tolerance for each species was consulted in the CABI Invasive Species Compendium (2018).

The level of confidence in the likelihood of climatic suitability was based on the quality of information available. A high level of confidence was assigned if both air temperature values were available; a medium level of confidence was assigned if only one of the temperature values was available but there was information on the species being naturalised or not elsewhere with similar climatic conditions to those in Spain (i.e. Mediterranean or temperate climate); and a low level of confidence was assigned if only one of the temperature values was available or if the species was naturalised or not elsewhere with similar climatic conditions to those in Spain.

Impact assessment

There are different ways to rate impacts in risk assessments. Some are based on their significance and intensity, some on the number of impacts (see table 3 in Vilà et al. 2019). To quantify the intensity of impacts requires a throughout screening of all the scientific literature, an aim that was above our man-power capacity. As we had many species to assess and our approach is by Horizon-scanning, we identified a broad range of potential impact types, including socioeconomic impacts. For each invasive or potentially invasive species, we assigned binary scores (yes/no) to the 11 potential impact mechanisms on the environment, following Blackburn et al. (2014): competition, hybridisation, disease transmission, parasitism, poisoning, toxicity and allelopathy, biofouling, interaction with other invasive non-native species, nutrient cycling, physical modification of the habitat, natural succession and disruption to food webs. We also included potential impacts on four socioeconomic aspects: human health (such as allergenic pollen), infrastructures, agriculture and forestry and other sectors (e.g. livestock, domestic animals). The vast majority of the data concerning impacts was retrieved from the CABI Invasive Species Compendium (2018). For cases in which the CABI compendium did not provide sufficient information, the Global Invasive Species Database (Invasive Species Specialist Group 2015) was consulted. Information on pollen allergenicity was found in the Allergome database (Mari et al. 2009).

We compared the numeric results of potential environmental (0–11) and socioeconomic (0–4) impacts between the different invasion status groups of non-native species (i.e. not in the wild, casual, naturalised and invasive). We used R software to perform a multiple comparison using Tukey’s range test, fitted in the generalised linear model (glm) by quasi-Poisson regression.

We consider median values for both environmental and socioeconomic impacts as the threshold for the classification between species with a high and low number of impacts. Species with environmental or socioeconomic impacts at or above the thresholds were included in the Attention List, while species with both environmental and socioeconomic impacts below the threshold formed the Watch List.

Societal interest analysis of Attention List species

Google is currently the most popular information search engine (Purcell et al. 2012) and it is quite useful for forecasting consumption and commerce (Vosen and Schmidt 2011). Google Trends (http://trends.google.es) has turned out to be a valuable tool to measure the level of interest of internet users on topics, species, events, questions etc., based on keywords and thus it has already been applied for this purpose in other research (Vosen and Schmidt 2011, Burivalova et al. 2018). Google Trends provides monthly data in a defined temporal range of regional trends of five keywords at a time, always relative to the highest value which is set to 100. We used Google Trends to analyse the level of interest of Spanish users in the Attention List species. We are aware that a species ranking high in interest does not necessarily mean that users are more interested in purchasing them. The reasons behind the searches for these species are not known, but they indicate how popular the species are in society in general.

To standardise those relative values, we used the R pack "gtrendsR" v. 1.4.2. We first made a systematic examination of the scientific names of every species listed in the Attention List in the temporal range from January 2004 to December 2016 to identify the species with the highest trend value. We used the scientific names to standardise our search; some species consulted do not have vernacular names in Spanish and some others may have different names. As the Google Trends tool allows entering 5 keywords at a time, we carried out a first examination forming one initial group of five species to analyse and taking the highest value species in this first group. Then, we compared this highest ranked species with the next four species and again selected the species with the highest value in this new group. Systematically repeating this algorithm with the rest of the species allowed us to identify the species with the highest trend value, Robinia pseudoacacia. The highest value for this species is set equal to 100 and this was assigned as our control species. Then, in a second systematic consultation of Google Trends, we obtained the trend data for the rest of the species by comparing each one with the control, in order to standardise the values.

For each species, we obtained a standard trend value (STV) as the highest value of the monthly trend in the complete temporal range of each species, relative to the optimal value of 100 of the control species. After that, we also performed a systematic consultation of Google Trends for the species in the Green List and the Priority List.

We compared differences in STV of the Attention List species across the different invasion status groups of species within the list (i.e. not in the wild, casual, naturalised and invasive). We used R software to perform a multiple comparison using Tukey’s range test, fitted in the generalised linear model (glm) by quasi-Poisson regression. We also compared the STV of the species in the Priority list and the Green list, in order to check whether the STV index correlates with invasion itself.

Invasion risk assessment of Attention List species

We used an adaptation of the invasion risk assessment (WRA) protocol (Pheloung et al. 1999) for Spain (Gassó et al. 2010) in order to rank the species in the Attention list. The WRA scores range from –14 (benign species) to 29 (maximum risk). Three levels of invasion risk were considered: rejected, species likely to be high risk (score > 6); accepted, species with a low score (< 1); and species that need further evaluation, those with intermediate scores (1–6).

We compared the scores of the WRA of the Attention List species across the different invasion status groups of species within the list (i.e. not in the wild, casual, naturalised and invasive). We used R software to perform a multiple comparison using Tukey’s range test, fitted in the generalised linear model (glm) by quasi-Poisson regression.

Prioritisation of Attention List species

We calculated a Priority Index for each species in the Attention list based on impact assessment, WRA score and STV according to the following equation:

PIi=(100×Ei11+100×Si4+100×WRAi29+STVi)/4

where: PIi = Priority Index for species i; Ei = number of environmental impacts for species i; Si = number of socioeconomic impacts for species i; WRAi = Weed Risk Assessment score for species i; STVi = Standard Trend Value for species i.

The impact factors were relative to the 11 environmental and 4 socioeconomic impacts which represent the maximum possible impacts in the assessment. The WRA-factor was relative to 29, which is the maximum possible value in the WRA protocol. The STV is already represented as a percentage and thus no conversion is needed.

Within each invasion status group, we listed species in decreasing order of their Priority Index and highlighted those with a Priority Index at or above the median.

Data resources

The data underpinning the analysis, reported in this paper, are deposited in the Zenodo repository at https://doi.org/10.5281/zenodo.3367257 (Bayon and Vilà 2019).

Results

Of the 914 taxa identified to species, 199 were native to Spain and 15 were archaeophytes. Of the 700 remaining non-native species, we did not find sufficient information on invasion status, climatic suitability or invasiveness elsewhere for 430 species (Data deficient list; Appendix 4) in the consulted databases (Invasive Species Specialist Group 2015; CABI 2018). For the remaining 270 non-native species, 71 taxa were not in the wild, 99 were casual, 70 naturalised and 30 invasive in Spain. Of the invasive species in Spain, eight are regulated by the Spanish Catalogue of Non-native Invasive Species (BOE 2013) and one of them, Pennisetum setaceum, is also regulated by the List of Invasive Alien Species of Union Concern (2016, 2017).

Nineteen species not in the wild, 30 casual and 24 naturalised species are climatically suitable and invasive elsewhere and thus considered potential invaders. These species, in addition to the 22 already invasive non-regulated species, were assessed for impact (Table 1).

Classification of commercial ornamental plant taxa in Spain according to their invasion status and climatic suitability. Colour codes correspond to those in Fig. 1: Priority List (red, Table 2), Impact Risk Analysis (orange), Green List (green, Table 4) and Uncertainty List (grey, Appendix 3).

N Climatic suitable Not Climatic suitable Low confidence in likelihood on climatic suitability Not enough information about climatic suitability Invasive elsewhere Not invasive elsewhere
Total taxa in nurseries 1036
Taxa excluded 122
Total species listed 914
Native 199
Archeophyte 15
Non-native (non-archeophyte) 700
Invasive – Regulated 8
Invasive – Not Regulated 22
Naturalised 70 24 46
Casual 100 36 2 4 58
Casual – Climatic Suitable 30 6
Casual – Not Climatic Suitable 1 1
Not in the wild 71 34 10 27
Not in the wild – Climatic Suitable 19 15
Not in the wild – Not Climatic Suitable 4 6
Data deficient 430

Impact Assessment

We assessed the potential impact of the above-mentioned 19 not in the wild, 30 casual, 24 naturalised and 22 invasive species that are climatically suitable and invasive elsewhere. The global median value for environmental impacts was three and the median for socioeconomic impacts was one. Therefore, species with impacts at or above these values were included in the Attention List. This included eleven not in the wild (58%), 22 casual (73%), 20 naturalised (83%) and 15 invasive species (68%). We did not find significant differences in the number of environmental or socioeconomic impacts across any pair of species status groups (Fig. 2).

Figure 2.

Environmental (a) and socioeconomic (b) impacts of invasive and potentially invasive ornamental plant species. P-values for Tukey’s range tests for environmental impacts: not in the wild – casual: p = 0.833; not in the wild – naturalised: p = 0.498; not in the wild – invasive: p = 0.926; casual – naturalised: p = 0.904; casual – invasive: p = 0.997; naturalised – invasive: p = 0.845. P-values for Tukey’s range tests for socioeconomic impacts: not in the wild – casual: p = 0.790; not in the wild – naturalised: p = 0.526; not in the wild – invasive: p = 0.916; casual – naturalised: p = 0.947; casual – invasive: p = 0.994; naturalised – invasive: p = 0.875. Dashed red line represents the global median of impacts and the threshold for species in the Attention List (at and above the line, Table 3) and Watch List (below the line, Appendix 2)

Within each invasion status, the species with the highest number of environmental impacts included the invasive Robinia pseudoacacia (7), Agave sisalana (6) and Elaeagnus angustifolia (6); the naturalised Ficus pumila (7), Ficus rubiginosa (6), Lupinus polyphyllus (6) and Sansevieria trifasciata (6); the casual Wisteria sinensis (8) and Grevillea robusta (7); and the not in the wild Nymphaea odorata (7).

Species with the highest number of socioeconomic impacts were the invasive Robinia pseudoacacia (3), Acacia longifolia (3), Eucalyptus globulus (3) and Lantana camara (3); the naturalised Lupinus polyphyllus (3), Rhus typhina (3) and Tagetes minuta (3); the casual Miscanthus sinensis (3), Portulaca oleracea (3) and Sesbania punicea (3); and the not in the wild Allamanda cathartica (3).

Species listing

The 270 non-native species with available data were classified into the following five lists:

The Priority List contains eight regulated invasive species that were still commercially available in nurseries (Table 2).

Priority List. Includes invasive species regulated by the Spanish Catalogue of Non-native Invasive Species (BOE 2013) or the List of Invasive Alien Species of Union Concern (European Commission 2016, 2017). Native distribution: Afr: Africa; As: Asia (Temperate); Aus: Australia; NAm: North America; SAm: South and Central America.

Species Family Native distribution Regulated in Spain Regulated in EU
Acacia dealbata Fabaceae Aus Yes No
Agave americana Agavaceae SAm Yes No
Ailanthus altissima Simarubaceae As Yes No
Buddleja davidii Scrophulariaceae As Yes No
Cortaderia selloana Poaceae SAm Yes No
Opuntia ficus-indica Cactaceae NAm Yes No
Pennisetum setaceum Poaceae Afr Yes Yes
Tradescantia fluminensis Commelinaceae SAm Yes No

The Attention List (Table 3) is composed of 68 species, including 11 not in the wild, 22 casual, 20 naturalised and 15 invasive.

Attention List. Includes all invasive and potentially invasive species with ≥ 3 environmental or ≥ 1 socio-economic potential impacts, classified as: a) not in the wild, b) casual, c) naturalised and d) invasive species, presented in decreasing Priority Index order. Native distribution: Afr: Africa; As: Asia (Temperate); AT: Asia (Tropical); Aus: Australia; Eur: Europe; NAm: North America; Pac: Pacific; SAm: South and Central America. Weed Risk Assessment (WRA): scores 1–6 indicate that the species needs further evaluation; scores > 6 indicate that the species is rejected. STV: Standard Trend Value (0-100). Priority Index is calculated following the equation: Priority index = ((100 × Ei) / 11 + (100× Si) / 4 + (100 ×WRA) / 29 +STV) / 4 where: Ei = environmental impacts; Si = socioeconomic impacts. * Species with Priority Index ≥ 35 have been highlighted with an asterisk.

Family Native distribution Impacts WRA Trends Prior. Index
Environment Socio-economics Score Evaluation STV Evaluation
a) Species not in the wild
Cinnamomum camphora* Lauraceae As 4 2 17 Reject 35 Less Interesting 45
Cotoneaster horizontalis* Rosaceae As, AT 3 1 26 Reject 37 Less Interesting 45
Physalis angulata* Solanaceae NAm, SAm, Pac 4 2 22 Reject 0 Not Interesting 41
Allamanda cathartica* Apocynaceae SAm 4 3 11 Reject 0 Not Interesting 37
Nymphaea odorata* Nymphaeaceae NAm 7 2 9 Reject 0 Not Interesting 36
Leptospermum scoparium* Myrtaceae Aus 3 1 13 Reject 43 Less Interesting 35
Cornus sericea Cornaceae NAm 4 1 22 Reject 0 Not Interesting 34
Berberis thunbergii Berberidaceae As 4 1 12 Reject 27 Less Interesting 32
Alocasia macrorrhizos Araceae AT 4 0 13 Reject 0 Not Interesting 20
Euonymus fortunei Celastraceae As 4 0 7 Reject 0 Not Interesting 15
Archontophoenix cunninghamiana Arecaceae Aus 4 0 4 Evaluating 0 Not Interesting 13
b) Casual species
Portulaca oleracea* Portulacaceae Afr, EUr 4 3 15 Reject 54 Interesting 54
Cestrum nocturnum* Solanaceae SAm 4 2 9 Reject 80 Very Interesting 49
Wisteria sinensis* Fabaceae As 8 2 9 Reject 43 Less Interesting 49
Kalanchoe daigremontiana* Crassulaceae Afr 5 1 22 Reject 37 Less Interesting 46
Pinus radiata* Pinaceae NAm 3 2 12 Reject 60 Interesting 45
Nandina domestica* Berberidaceae As, AT 5 2 9 Reject 43 Less Interesting 42
Casuarina equisetifolia* Casuarinaceae Aus 5 2 7 Reject 45 Less Interesting 41
Miscanthus sinensis* Poaceae AT 6 3 9 Reject 0 Not Interesting 40
Paulownia tomentosa* Paulowniaceae As, AT 4 1 19 Reject 27 Less Interesting 38
Zantedeschia aethiopica* Araceae Afr 0 1 15 Reject 70 Interesting 37
Physalis peruviana* Solanaceae SAm 5 2 8 Reject 22 Not Interesting 36
Grevillea robusta* Proteaceae Aus 7 1 2 Evaluating 45 Less Interesting 35
Sesbania punicea* Fabaceae SAm 2 3 13 Reject 0 Not Interesting 35
Gypsophila paniculata Caryophyllaceae As, Eur 6 1 6 Evaluating 17 Not Interesting 29
Eugenia uniflora Myrtaceae SAm 5 0 18 Reject 0 Not Interesting 27
Spiraea japonica Rosaceae As, AT 4 0 11 Reject 28 Less Interesting 26
Tecoma stans Bignoniaceae NAm, SAm 4 1 11 Reject 0 Not Interesting 25
Prunus serotina Rosaceae NAm 6 0 12 Reject 0 Not Interesting 24
Morus nigra Moraceae As 3 0 4 Evaluating 45 Less Interesting 22
Eucalyptus sideroxylon Myrtaceae Aus 3 0 14 Reject 0 Not Interesting 19
Yucca aloifolia Agavaceae NAm 3 1 4 Evaluating 0 Not Interesting 17
Cereus uruguayanus Cactaceae SAm 3 0 3 Evaluating 0 Not Interesting 9
c) Naturalised species
Lupinus polyphyllus* Fabaceae NAm 6 3 27 Reject 0 Not Interesting 56
Canna indica* Cannaceae SAm 8 1 24 Reject 35 Less Interesting 54
Rhus typhina* Anacardiaceae NAm 5 4 15 Reject 0 Not Interesting 49
Phragmites australis* Poaceae NAm 2 2 27 Reject 35 Less Interesting 49
Tagetes minuta* Asteraceae NAm 4 3 22 Reject 0 Not Interesting 47
Imperata cylindrica* Poaceae AT 7 1 24 Reject 0 Not Interesting 43
Ficus pumila* Moraceae AT 3 3 5 Evaluating 35 Less Interesting 39
Phoenix canariensis* Arecaceae Afr 4 1 6 Evaluating 71 Interesting 38
Melia azedarach* Meliaceae AT, Aus 4 0 12 Reject 71 Interesting 37
Psidium cattleianum* Myrtaceae SAm 6 1 20 Reject 0 Not Interesting 37
Albizia julibrissin Fabaceae As 3 0 14 Reject 62 Interesting 34
Ficus rubiginosa Moraceae Aus 6 1 7 Reject 26 Less Interesting 32
Broussonetia papyrifera Moraceae As 5 2 2 Evaluating 27 Less Interesting 32
Ziziphus jujuva Rhamnaceae As, AT, Aus 5 1 17 Reject 0 Not Interesting 32
Pennisetum villosum Poaceae Afr 3 0 25 Reject 0 Not Interesting 28
Sansevieria trifasciata Asparagaceae Afr 4 0 12 Reject 35 Less Interesting 28
Bacopa monnieri Plantaginaceae NAm, SAm, As, Eur 2 1 16 Reject 10 Not Interesting 27
Adiantum raddianum Pteridaceae SAm 3 1 13 Reject 7 Not Interesting 26
Atriplex semibaccata Amaranthaceae Aus 3 0 15 Reject 0 Not Interesting 20
Annona cherimola Annonaceae SAm 1 1 0 Accepted 0 Not Interesting 9
d) Invasive species
Robinia pseudoacacia* Fabaceae NAm 7 3 15 Reject 100 Very Interesting 73
Lantana camara* Verbenaceae SAm 5 3 25 Reject 67 Interesting 68
Eucalyptus globulus* Myrtaceae Aus 4 3 21 Reject 35 Less Interesting 55
Acacia longifolia* Fabaceae Aus 4 3 23 Reject 0 Not Interesting 48
Acacia saligna* Fabaceae Aus 5 1 22 Reject 23 Not Interesting 42
Leucaena leucocephala* Fabaceae NAm 5 0 21 Reject 35 Less Interesting 38
Elaeagnus angustifolia* Elaeagnaceae As 6 0 21 Reject 19 Not Interesting 36
Lonicera japonica* Caprifoliaceae As, AT 3 1 14 Reject 39 Less Interesting 35
Agave sisalana* Agavaceae SAm 6 2 10 Reject 0 Not Interesting 35
Psidium guajava Myrtaceae NAm 4 1 19 Reject 0 Not Interesting 32
Gleditsia triacanthos Fabaceae NAm 4 0 10 Reject 41 Less Interesting 28
Phormium tenax Xanthorrhoeaceae Pac 3 0 10 Reject 35 Less Interesting 24
Bidens aurea Asteraceae NAm 1 2 5 Evaluating 18 Not Interesting 24
Stenotaphrum secundatum Poaceae Afr 5 0 13 Reject 0 Not Interesting 23
Pasiflora caerulea Passifloraceae SAm 3 0 6 Evaluating 0 Not Interesting 12

The Watch List contains 27 species: eight not in the wild, eight casual, four naturalised and seven invasive, but below the threshold for environmental and socioeconomic impacts (Appendix 2).

The Green List is represented by only seven species: one casual and six not in the wild taxa that are not climatically suitable nor invasive elsewhere (Table 4). Finally, the Uncertainty List was formed by 161 species, in which: 46 are not in the wild (27 with low confidence on climatic suitability, 15 not invasive elsewhere but climatically suitable, four not climatically suitable but invasive elsewhere), 69 are casual (4 with low confidence on climatic suitability, 58 with no available information on climatic suitability, six not invasive elsewhere but climatically suitable and one not climatically suitable but invasive elsewhere) and 46 are naturalised not invasive elsewhere (Appendix 3).

Green List. Includes non-native non-invasive species with very low invasion potential. Native distribution: As: Asia (Temperate); AT: Asia (Tropical); SAm: South and Central America. Status in Spain: N: Not in the wild, C: Casual.

Species Family Native distribution Status in Spain
Averrhoa carambola Oxalidaceae AT N
Celosia argentea Amaranthaceae AT N
Ficus benjamina Moraceae AT N
Mangifera indica Anacardiaceae As – AT N
Nelumbo nucifera Nelumbonaceae AT N
Pogostemon helferi Lamiaceae AT N
Senna corymbosa Fabaceae SAm C

Societal interest analysis of Attention List species

In the Google Trends systematic examination of the 68 Attention List species, maximum trend values were observed for Robinia pseudoacacia – March 2004 – and therefore we used this record as our control species.

Within the Attention list, the most noteworthy species (higher STV) included: the invasive Robinia pseudoacacia (100) and Lantana camara (67); the naturalised Phoenix canariensis (71) and Melia azedarach (71); the casual Cestrum nocturnum (80) and Zantedeschia aethiopica (70); and, far from the previous groups, the not in the wild Leptospermum scoparium (43). Complete results of the STV analysis are shown in Table 3. There were no significant differences in STV between any pair of invasion status groups of species (Fig. 3). Similarly, there were no differences between the species in the Priority list and the Green List (p=0.967).

Figure 3.

Society interest in ornamental non-native plant species classified by their invasion status. STV: Standard Trend Value. P-values for Tukey’s range tests: not in the wild – casual: p = 0.373; not in the wild – naturalised: p = 0.783; not in the wild – invasive: p = 0.436; casual – naturalised: p = 0.794; casual – invasive: p = 1; naturalised – invasive: p = 0.860.

Invasion risk assessment of Attention List species

In the WRA, all species in the Attention List were rejected, except for 11 that required further evaluation and only one, Annona cherimola, that was accepted (Table 3).

Within each invasion status, the highest WRA scores were for the invasive Lantana camara (25), Acacia longifolia (23), Acacia saligna (22), Elaeagnus angustifolia (21), Eucalyptus globulus (21) and Leucana leucocephala (21); the naturalised Phragmites australis (27), Lupinus polyphyllus (27), Pennistum villosum (25), Canna indica (24) and Imperata cylindrica (24); the casual Kalanchoe daigremontiana (22), Pawlownia tomentosa (19) and Eugenia uniflora (18); and the not in the wild Cotoneaster horizontalis (26), Cornus sericea (22) and Physalis angulata (22). For every invasion status, the species requiring further evaluation accounted for less than 25%. There were no significant differences in WRA scores between any pair of invasion status groups of species (Fig. 4).

Figure 4.

Weed risk assessment (WRA) score in ornamental non-native plant species classified by their invasion status in Spain. P-values for Tukey’s range tests: not in the wild – casual: p = 0.392; not in the wild – naturalised: p = 0.983; not in the wild – invasive: p = 0.951; casual – naturalised: p = 0.101; casual – invasive: p = 0.086; naturalised – invasive: p = 0.997.

Prioritisation of Attention List species

The median value of Priority Indices was 35. Species with a Priority Index ≥ 35 are highlighted in Table 3. Within each invasion status, the highest Priority Indices in invasive species were found for Robinia pseudoacacia (73), Lantana camara (68) and Eucalyptus globulus (55); in naturalised species Lupinus polyphyllus (56) and Canna indica (54); in casual species Portulaca oleracea (54), Cestrum nocturnum (49) and Wisteria sinensis (49); and in not in the wild species Cinnamimum camphora (45) and Cotoneaster horizontalis (45). There were no significant differences between any pair of invasion status groups of species (Fig. 5).

Figure 5.

Priority Index in ornamental non-native plant species classified by their invasion status in Spain. P-values for Tukey’s range tests: not in the wild – casual: p = 0.981; not in the wild – naturalised: p = 0.860; not in the wild – invasive: p = 0.633; casual – naturalised: p = 0.958; casual – invasive: p = 0.748; naturalised – invasive: p = 0.953. Dashed red line represents the global median of Priority Index (=38). Species at or above this line should be considered in prioritisation, as shown in table 3.

Discussion

Nurseries and the commercial introduction of non-native plant species are the main deliberate pathways for plant invasions (Van Kleunen et al. 2018). Some of the most harmful invasive plant species in the wild are non-native species introduced for commercial purposes (Hulme 2007). In Spain, non-native plants represent the vast majority of species sold by nurseries (77%) and 30 of these species have been reported as invasive in the peninsular territory of Spain. The regulation of non-native invasive plant species is necessary. However, nurseries often do not fully comply with commercial restrictions (Wirth et al. 2004; Cronin et al. 2017; Touza et al. 2014). Besides the Spanish (BOE 2013) and European (European Commission 2016, 2017) regulations on non-native invasive species and similar to what happens in other countries, there are eight regulated species that, although being regulated, were still commercially available in the country at the time of this study (Appendix 1), as indicated in the Priority List. One of them, Pennisetum setaceum, was also been included under European regulation, although this inclusion is more recent than the study of the nurseries for this study. Therefore, there is a pressing need to enforce the current legislation, as well as to raise public awareness to prohibit the trade of these species.

Furthermore, because the deliberate transport, commerce and planting of non-native plant species can be controlled, all the invasive and potentially invasive species compiled into the Attention List could be considered for regulation, following the advice of the European Parliament and Council (2014). While some of these species have been introduced to provide an immediate economic benefit, such as Eucalyptus globulus and other species of the same genus (Touza et al. 2014), their impacts on the environment, as well as on some human activities besides the forestry sector, suggest that their regulation should be considered. In addition, the costs derived from the control of invasive species can be quite significant (Pimentel et al. 2005) and are not compensated for by their economic benefits.

The levels of potential impacts of species in the Attention List are independent of their invasion status in Spain. That is, current non-invasive species have the potential to cause as many impacts as invasive species. This result supports previous empirical studies indicating that invasiveness does not always translate to impacts (Ricciardi and Cohen 2007). Despite the fact that some of these species were introduced a long time ago and are already invasive, such as Ailanthus altissima introduced into Spain in 1818 or Acacia dealbata in 1824 (Sanz Elorza et al. 2004), others have possibly been introduced recently as ornamental plants and thus have not had enough time for establishment and dispersal (Pemberton and Liu 2009). As a precautionary measure to avoid their impacts, there is a need to prevent the introduction of any non-native species listed in the Attention List and to conduct a complete risk assessment to study the possibility of their being regulated.

As the threshold number of environmental and socioeconomic impacts required for a species to be included or not in the Attention List is based on median values, it may exclude some species that have high risks of invasion despite a low number of impact types or species with still unknown impacts. In fact, the Watch List contains species that are well known to be invasive elsewhere, such as Acer negundo or Eriobotrya japonica, which cause few, but important, impacts. More detailed research on the potential type of impacts of the species in the Watch List, as well as conducting a WRA for these species, would allow for more adequate prioritisation of these species that are of major concern after those in the Priority and Attention Lists.

We are confident that the potential invasion of Attention List species is robust given the positive results of the WRA, in which only one of the 68 species listed was classified as accepted (i.e. low invasion risk). The proportion of species rejected by the WRA was very high and similar in all status groups of species, with a likely low incorporation of false positives (Andreu and Vilà 2010). Furthermore, our WRA analysis warns that species which are not in the wild, still have the potential to become invasive, reaching scores as high as those of already naturalised or invasive plants.

Likewise, with our analysis on the STV, we cannot infer causality between societal interest and increased commerce. In fact, the STV is not a good predictor of invasion status; the absence of differences between STV of the species in the Priority list and the Green list shows that the STV is not related with invasion. Nevertheless, greater interest, as reflected in Google statistics, can still be an indicator of increased consumption and trade (Vosen and Schmidt 2011) and greater interest might promote greater propagule pressure and greater potential to become established (Dehnen-Schmutz et al. 2007a; Johnston et al. 2009; Blackburn et al. 2013; García-Díaz et al. 2015). Thus, we think that the STV continues to have value, not as a predictor of invasion, but as a factor to be considered during prioritisation of the species within each invasion group.

Our approach is similar to previous Horizon-scanning analyses for non-native species (Roy et al. 2014, Roy et al. 2019) with the differences being that, in our study case, all the species are already in the region of analysis and the scoring is based on more parameters than just their potential to establish and cause impacts. We provide a Priority Index that includes the risk of invasion, the level of potential impacts and the popularity of the species. Therefore, it offers an integrative score that may be of interest to environmental administrations and management services as a valuable tool to support decision-making. The homogeneity in the Priority Index across the invasion status groups of species confirms that the potential for invasion and the impact risks are independent of the actual invasion status of the species (Roberts et al. 2011; Gassó et al. 2010). Therefore, this index may even be useful for identifying current non-invasive species that, even if not in the wild, are potentially invasive. Indeed, our species Prioritisation List has already been used to identify species with the potential to be invasive in Gibraltar, an overseas territory of the United Kingdom which buys all its ornamental plants from neighbouring Spain according to the UKOTs Horizon Scanning and Biosecurity Workshop that took place on 21–24 January 2019 (K. Bensusan, pers. Com).

We also generated an Uncertainty List composed of species that probably do not represent an immediate invasion risk. For fifty-six percent of the species listed, we lack sufficient confidence in the likelihood of climatic suitability (or we have no information about it). Even if the species in the Uncertainty List do not become established in Spain due to their climatic requirements, or they are not invasive elsewhere, we need to be aware that these two criteria can change over time. For example, a particular climate change scenario could cause climatically unsuitable species to become suitable in the future (Mainka and Howard 2010).

Unfortunately, we could not find information on the status, invasive potential and climatic suitability of 61% of the non-native species sold in nurseries. There is a worrying possibility that the Data Deficient List includes some potentially invasive species that are not considered in the two major databases consulted (CABI Datasheets 2018; Invasive Species Specialist Group 2015). Additional research, as well as consultation of the primary literature, is needed to allow reclassifying species from the Data Deficient List, a task that would require the expertise of a larger team of scientists (Roy et al. 2019; González-Moreno et al. 2019). The immediate task would be to use the new available GLONAF database to identify invasive species elsewhere (van Kleunen et al. 2019).

Finally, we provide a Green List of non-native species with very low invasion potential. Promoting preferences for non-invasive species in horticulture can be a valuable endeavour in order to make regulations easier to comply with (Gagliardi and Brand 2007). Involving the horticultural industry in the dissemination of plant invasion risks and in the development of regulations has been shown to be effective (Humair et al. 2014). This Green List can be a starting point for the establishment of voluntary codes of conduct amongst nursery owners (Reichard 2004; Gagliardi and Brand 2007; Robinson et al. 2017). However, it is prudent not to forget that propagule pressure is an important factor determining invasion (Lockwood et al. 2005; 2009; Johnston et al. 2009).

If species in the Green List are planted frequently, in large quantities and in many locations, this scenario can be changed. For this reason, the Green List presented here is short and tentative; further and more in-depth research is needed on the Uncertainty List so as to possibly enlarge this Green List. Planting native species will always be the preferable alternative.

The present research is preliminary in nature and the authors are aware of the clear limitations of the conclusions. However, we consider it can be a very useful and complete tool to establish priorities in long lists of species for which not much information is available and it represents a good starting point for more thorough and detailed risk analyses that allow the improvement and implementation of new and more efficient forms of regulation of invasive species.

Based on our prioritization list analysis, we provide the following recommendations: 1) there is a need to reinforce the current legislation and implement systems that guarantee its compliance regarding the species of the Priority List; 2) invasive species in the Attention List should be considered for regulation; 3) established, casual and not in the wild species in the Attention List, especially those with higher Priority Index values, should be included in a monitoring programme to prevent future invasions; 4) species in the Watch List should be included in an early warning programme if they are not yet in the wild and monitored if they are already established in a few localities; 5) species in the Uncertainty List require further evaluation in order to be reclassified into Attention, Watch or Green Lists; finally 6) species in Data Deficient List require further information on their status, invasive potential or climatic suitability in order to be reclassified into Attention, Watch or Green lists.

This research also reveals the limited responsibility and awareness by some commercial nurseries regarding the sale of invasive species. A better monitoring and tracking system for the species for sale and more rigorous inspections in nurseries are very necessary (Touza et al. 2014). Citizen awareness through the dissemination of knowledge about invasive non-native species, as well as citizen science projects working with gardeners, can be useful tools to reduce their demand and consumption as suggested in other studies (Reichard 2004; Gagliardi and Brand 2007; Robinson et al. 2017; Dehnen-Schmutz and Conroy 2018). Having a national registry of ornamental plant species available for sale and the requirement of a risk analysis for the introduction of new species in it, is also a recommendation to be considered.

Acknowledgements

This study was funded by the project IMPLANTIN (CGL2015-65346-R). Á. Bayón is hired by the Biological Station of Doñana (EBD-CSIC) thanks to a Grant for Predoctoral Contracts for the Training of Doctors 2015 awarded by the Ministerio de Ciencia, Innovación y Universidades of Spain and co-financed by the European Social Fund (BES-2015-072929). We thank P. Castro, O. Godoy and F. Essl, S. Vanderhoeven, P. Hulme and the associated editor for comments on previous versions of the manuscript and J. Arroyo for tutoring the thesis project at the University of Seville.

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Appendix 1

Nurseries. The list of taxa was compiled through the systematic consultation of Spanish nursery catalogs which provide information on plants for sale. As shown in the graph below, the number of taxa did not increase after the 15th catalog was consulted. Our database included a total of 1036 taxa from 21 nurseries. Notice that these nurseries are distributed across all biogeographic regions of mainland Spain.

Nursery Source Access date Province Num. taxa
1 Viveros Plantamus https://plantamus.com 11/12/15 A Coruña 286
2 Viveros Sanchez http://viverossanchez.com 01/04/16 Guadalajara 638
3 Viveros Maiplant http://www.maiplant.com 02/23/16 Alicante 66
4 Alberola Viveros http://www.alberolaviveros.com 02/23/16 Valencia 510
5 Viveros Bargues http://www.viverosbargues.com 02/24/16 Valencia 97
6 Viveros Rucat http://www.viverosrucat.es 01/26/16 Madrid 189
7 Viveros Veron http://viverosveron.com 01/26/16 Zaragoza 92
8 Garden Center Campo Grande http://www.campogrande.es 01/31/16 Valladolid 214
9 Plantas del Sueve http://www.delsueve.com 02/01/16 Asturias 217
10 Viveros Urkiondo http://www.urkiondo.com 02/09/16 Guipuzkoa 174
11 Viveros Barra http://viverosbarra.es 05/01/16 Leon 410
12 Viveros Coplant http://www.coplant.es 05/20/16 Pontevedra 137
13 Viveros Borrazas http://www.viverosborrazas.com 06/11/16 A Coruña 231
14 Viveros Zuaime http://www.viveroszuaime.es 06/14/16 Granada 238
15 Viveros Sevilla http://www.viverossevilla.com 06/16/16 Sevilla 180
16 Viveros Ferca http://viverosferca.com 07/28/16 Ciudad Real 162
17 Viveros Ibañez http://www.viverosibanez.es 09/20/16 Zaragoza 171
18 Viveros Corma http://www.corma.es 09/30/16 Barcelona 383
19 Viveros Canós http://viveroscanos.com 09/30/16 Badajoz 132
20 Viveros Perica http://viverosperica.com 10/03/16 La Rioja 195
21 Viveros Ametza http://www.viverosametza.com 10/03/16 Navarra 147

Appendix 2

Watch list. The Watch List includes invasive and potentially invasive species with potential impacts below median; classified as: a) not in the wild, b) casual, c) naturalized and d) invasive species. Native distribution: Afr: Africa; As: Asia (Temperate); AT: Asia (Tropical); Aus: Australia; NAm: North America; SAm: South and Center America.

Family Native distribution Impacts
Environment Socioeconomics
a) Species not in the wild
Berberis darwinii Berberidaceae SAm 2 0
Euonymus alata Celastraceae As 2 0
Ficus elastica Moraceae As 2 0
Fraxinus americana Oleaceae NAm 0 0
Gunnera manicata Gunneraceae SAm 2 0
Pyrus calleryana Rosaceae As, AT 0 0
Thevetia peruviana Apocynaceae NAm, SAm 0 0
Zelkova serrata Ulmaceae As, AT 0 0
b) Casual species
Ageratum houstonianum Asteraceae SAm 0 0
Aloe vera Liliaceae Afr 0 0
Corymbia citriodora Myrtaceae Aus 0 0
Erigeron karvinskianus Asteraceae SAm 0 0
Lagerstroemia indica Lythraceae As, AT 2 0
Salix babylonica Salicaceae As 0 0
Salvia microphylla Lamiaceae NAm 1 0
Trachycarpus fortunei Arecaceae As 1 0
c) Naturalized species
Alpinia zerumbet Zigimberaceae AT 2 0
Berberis aquifolium Berberidaceae NAm 1 0
Parthenocissus quinquefolia Vitaceae NAm 0 0
Passiflora edulis Passifloraceae SAm 2 0
d) Invasive species
Acer negundo Aceraceae NAm 1 0
Cyperus alternifolius Cyperaceae Afr 0 0
Eriobotrya japonica Rosaceae As 0 0
Eucalyptus camaldulensis Myrtaceae Aus 1 0
Oenothera biennis Onagraceae NAm 1 0
Pelargonium capitatum Geraniaceae Afr 2 0
Tropaeolum majus Tropaeolaceae SAm 0 0

Appendix 3

Uncertainty list. The Uncertainty List includes non-invasive and potentially non-invasive species which lack sufficient information, or those that do not meet the requirements to be included in the Green List; classified as: a) not in the wild, b) casual, and c) naturalized species. Native distribution: Afr: Africa; As: Asia (Temperate); AT: Asia (Tropical); Aus: Australia; Eur: Europe; NAm: North America; Pac: Pacific; SAm: South and Center America. Invasive elsewhere and climate suitability: Y: yes; N: no; Confidence in the likelihood of climatic suitability: H: high; M: med.

Family Native distribution Invasive elsewhere Climate suitability Confidence
a) Species not in the wild
Agave vivipara Agavaceae SAm Y Y L
Anubias barteri Araceae Afr N N L
Anubias hastifolia Araceae Afr Y N L
Anubias heterophylla Araceae Afr Y N L
Bacopa caroliniana Plantaginaceae NAm N Y L
Bismarckia nobilis Arecaceae Afr N N L
Blyxa japonica Hydrocharitaceae NAm N Y H
Brahea armata Arecaceae NAm N Y L
Brahea edulis Arecaceae NAm N Y L
Butia capitata Arecaceae SAm N Y L
Cabomba furcata Cabombaceae SAm N Y L
Campanula portenschlagiana Campanulaceae Eur N Y H
Carex buchananii Cyperaceae Aus N Y L
Chamaedorea seifrizii Arecaceae NAm N Y L
Clematis montana Ranunculaceae As N Y M
Cordyline australis Asparagaceae Aus N Y L
Corymbia ficifolia Myrtaceae Aus N Y L
Cotinus coggygria Anacardiaceae As N Y H
Cryptostegia madagascariensis Apocynaceae Afr Y N H
Cycas revoluta Cycadaceae As N Y L
Delonix regia Fabaceae Afr Y N H
Euphorbia lactea Euphorbiaceae SAm Y N M
Ficus lyrata Moraceae Afr N Y M
Ficus microcarpa Moraceae Aus Y Y L
Freesia alba Iridaceae Afr N Y M
Fuchsia magellanica Onagraceae SAm Y N M
Gardenia jasminoides Rubiaceae As, AT N Y M
Gaultheria mucronata Ericaceae SAm N Y L
Gaura lindheimeri Onagraceae NAm N Y M
Geum coccineum Rosaceae Eur N Y M
Glossostigma elatinoides Phrymaceae Aus N Y H
Lilaeopsis brasiliensis Apiaceae SAm N Y L
Liriope muscari Liliaceae As, NAm N Y L
Livistona chinensis Arecaceae As Y N L
Lonicera pileata Caprifoliaceae As N Y L
Loropetalum chinense Hamamelidaceae As N Y M
Mayaca fluviatilis Mayacaceae SAm N Y L
Myoporum tetrandrum Scrophulariaceae Aus N Y L
Ophiopogon japonicus Asparagaceae As N Y H
Opuntia microdasys Cactaceae NAm N Y H
Perovskia atriplicifolia Lamiaceae As N Y M
Pittosporum tenuifolium Pittosporaceae Pac N Y L
Pogostemon stellatus Lamiaceae AT, Aus N N L
Rotala wallichii Lythraceae As N Y L
Serenoa repens Arecaceae NAm N Y L
Vaccinium corymbosum Ericaceae NAm N Y M
b) Casual species
Acacia baileyana Fabaceae Aus N NA NA
Acer campestre Sapindaceae Afr, Eur N NA NA
Aloe arborescens Liliaceae Afr N NA NA
Aloe maculata Liliaceae Afr N Y H
Aloysia citrodora Verbenaceae SAm N Y H
Anthriscus cerefolium Apiaceae Eur N NA NA
Artemisia dracunculus Asteraceae As, Eur, NAm N NA NA
Brachychiton populneus Malvaceae Aus N NA NA
Caesalpinia gilliesii Fabaceae SAm N NA NA
Callistemon citrinus Myrtaceae Aus N NA NA
Calocedrus decurrens Cupressaceae NAm N NA NA
Campsis radicans Bignoniaceae NAm N NA NA
Catalpa bignonioides Bignoniaceae NAm N NA NA
Catharanthus roseus Apocynaceae Afr N NA NA
Cedrus deodara Pinaceae As N NA NA
Cedrus libani Pinaceae Eur N NA NA
Cercis siliquastrum Fabaceae Eur N NA NA
Coffea arabica Rubiaceae Afr N NA NA
Crassula ovata Crassulaceae Afr N Y M
Cupressus arizonica Cupressaceae NAm N NA NA
Cupressus macrocarpa Cupressaceae NAm N NA NA
Cydonia oblonga Rosaceae Eur N NA NA
Diospyros kaki Ebenaceae As N NA NA
Eucalyptus gunnii Myrtaceae Aus N NA NA
Euonymus japonicus Celastraceae As N NA NA
Euphorbia candelabrum Euphorbiaceae Afr N NA NA
Helianthus annuus Asteraceae NAm N NA NA
Hibiscus rosa-sinensis Malvaceae As N NA NA
Hibiscus syriacus Malvaceae As N NA NA
Hyacinthus orientalis Asparagaceae Afr, AT N NA NA
Jacaranda mimosifolia Bignoniaceae SAm N NA NA
Jasminum nudiflorum Oleaceae As N NA NA
Jasminum officinale Oleaceae As N Y H
Juglans nigra Juglandaceae NAm N NA NA
Koelreuteria paniculata Sapindaceae As N NA NA
Lagunaria patersonii Malvaceae Aus N NA NA
Larix decidua Pinaceae Eur N NA NA
Lepidium sativum Brassicaceae Afr N NA NA
Ligustrum ovalifolium Oleaceae As N NA NA
Lobelia erinus Campanulaceae Afr N NA NA
Lycium barbarum Solanaceae As N NA NA
Malus domestica Rosaceae As N NA NA
Mimosa pudica Fabaceae SAm Y Y L
Monstera deliciosa Araceae SAm N NA NA
Origanum majorana Lamiaceae As, Eur N NA NA
Phytolacca dioica Phytolaccaceae SAm N NA NA
Pinus canariensis Pinaceae Afr N NA NA
Pinus strobus Pinaceae NAm N NA NA
Pistacia vera Anacardiaceae As, Eur N NA NA
Pittosporum tobira Pittosporaceae As N NA NA
Plumbago auriculata Plumbaginaceae Afr N NA NA
Populus simonii Salicaceae As N NA NA
Prunus armeniaca Rosaceae NAm N NA NA
Prunus domestica Rosaceae Eur N NA NA
Pseudotsuga menziesii Pinaceae NAm N NA NA
Ruta graveolens Rutaceae Eur N NA NA
Salvia splendens Lamiaceae SAm Y N M
Sedum sexangulare Crassulaceae Eur N Y H
Sedum spurium Crassulaceae Eur N NA NA
Solanum pseudocapsicum Solanaceae SAm N NA NA
Spathodea campanulata Bignoniaceae SAm Y N L
Syringa vulgaris Oleaceae Eur N NA NA
Tagetes erecta Asteraceae NAm N Y M
Tagetes patula Asteraceae SAm N NA NA
Thunbergia alata Acanthaceae Afr Y N L
Tipuana tipu Fabaceae SAm N NA NA
Ulmus pumila Ulmaceae As, AT Y Y L
Washingtonia filifera Arecaceae NAm N NA NA
Zinnia elegans Asteraceae SAm N NA NA
c) Naturalized species
Actinidia chinensis Actinidiaceae As N
Aeonium arboreum Crassulaceae Afr N
Aesculus hippocastanum Sapindaceae Eur N
Alnus cordata Betulaceae Eur N
Ammannia coccinea Lythraceae NAm N
Anethum graveolens Apiaceae Afr N
Anthurium scherzerianum Anthuriaceae As-Eur N
Aptenia cordifolia Aizoaceae Afr N
Aquilegia vulgaris Ranunculaceae As, Eur N
Austrocylindropuntia cylindrica Cactaceae SAm N
Bougainvillea glabra Nyctaginaceae SAm N
Cedrus atlantica Pinaceae Afr N
Cerastium tomentosum Caryophyllaceae Eur N
Chamaecyparis lawsoniana Cupressaceae NAm N
Chamaedorea elegans Arecaceae NAm N
Crataegus azarolus Rosaceae Afr, As, Eur N
Cuminum cyminum Apiaceae Eur N
Cupressus sempervirens Cupressaceae Eur N
Erysimum odoratum Brassicaceae Eur N
Euphorbia milli Euphorbiaceae Afr N
Hydrangea macrophylla Hydrangeaceae As N
Hydrocotyle verticilata Araliaceae NAm N
Hypericum calycinum Hypericaceae Eur N
Impatiens walleriana Balsaminaceae Afr N
Laburnum anagyroides Fabaceae Eur N
Lonicera nitida Caprifoliaceae AS N
Mespilus germanica Rosaceae As, Eur N
Parthenocissus tricuspidata Vitaceae As, AT N
Pelargonium graveolens Geraniaceae Afr N
Pelargonium peltatum Geraniaceae Afr N
Petroselinum crispum Apiaceae Eur N
Phoenix dactylifera Arecaceae As N
Physocarpus opulifolius Rosaceae NAm N
Picea abies Pinaceae Eur N
Picea omorika Pinaceae Eur N
Prunus cerasifera Rosaceae Eur N
Prunus laurocerasus Rosaceae As N
Pyrostegia venusta Bignoniaceae SAm N
Quercus rubra Fagaceae NAm N
Salix viminalis Salicaceae Eur N
Sequoiadendron giganteum Cupressaceae NAm N
Styphnolobium japonicum Fabaceae As N
Tamarix parviflora Tamaricaceae Afr N
Vitis vinifera Vitaceae Eur N
Washingtonia robusta Arecaceae NAm N
Yucca gloriosa Agavaceae NAm N

Appendix 4

Data deficient list. The Data Deficient List includes species for which we did not have sufficient data for analysis. Native distribution: Afr: Africa; As: Asia (Temperate); AT: Asia (Tropical); Aus: Australia; Eur: Europe; NAm: North America; Pac: Pacific; SAm: South and Center America.

Species with deficient data Family Native distribution
Abelia chinensis Caprifoliaceae As
Abelia floribunda Caprifoliaceae Nam
Abies concolor Pinaceae NAm
Abies koreana Pinaceae As
Abies nordmanniana Pinaceae As, Eur
Abies procera Pinaceae NAm
Acacia floribunda Fabaceae Aus
Acacia pendula Fabaceae Aus
Acca sellowiana Myrtaceae SAm
Acer palmatum Sapindaceae As
Acer rubrum Sapindaceae NAm
Acer saccharinum Sapindaceae NAm
Acorus gramineus Acoraceae AT, AS
Actinidia arguta Actinidiaceae As
Actinidia deliciosa Actinidiaceae As
Adenium obesum Apocynaceae Afr
Aechmea fasciata Bromeliaceae SAm
Agapanthus africanus Amaryllidaceae Afr
Agave attenuata Agavaceae SAm
Agave bracteosa Agavaceae NAm
Agave filifera Agavaceae SAm
Agave guiengola Agavaceae SAm
Agave horrida Agavaceae SAm
Agave lechuguilla Agavaceae SAm
Agave macroacantha Agavaceae SAm
Agave salmiana Agavaceae SAm
Agave victoriae-reginae Agavaceae SAm
Agave xylonacantha Agavaceae SAm
Allagoptera arenaria Arecaceae SAm
Allium schoenoprasum Amaryllidaceae NAm
Alocasia wentii Araceae Aus
Aloe marlothii Liliaceae Afr
Aloe variegata Xanthorrhoeaceae Afr
Alpinia caerulea Zigimberaceae Aus
Alternanthera peruensis Amaranthaceae SAm
Alternanthera reinekii Amaranthaceae SAm
Alternanthera rosaeivolia Amaranthaceae SAm
Anacardium occidentale Anacardiaceae SAm
Andromeda polifolia Ericaceae Eur, As, NAm
Anemanthele lessoniana Poaceae Aus
Anemone blanda Ranunculaceae Eur
Anisodontea capensis Malvaceae Afr
Aphelandra squarrosa Acanthaceae SAm
Arabis alpina Brassicaceae AT
Araucaria araucana Araucariaceae SAm
Araucaria heterophylla Araucariaceae Aus
Archontophoenix alexandrae Arecaceae Aus
Archontophoenix purpurea Arecaceae Aus
Arctotis fastuosa Asteraceae Afr
Arenga engleri Arecaceae AT
Argyranthemum frutescens Asteraceae Afr
Arrojadoa rhodantha Cactaceae SAm
Asparagus setaceus Asparagaceae Afr
Aspidistra elatior Asparagaceae AT
Athyrium nipponicum Athyriaceae As
Aucuba japonica Garryaceae As
Balantium antarcticum Dicksoniaceae Aus
Banksia integrifolia Proteaceae Aus
Bauhinia purpurea Fabaceae SAm
Beaucarnea recurvata Asparagaceae SAm
Begonia cucullata Begoniaceae AT
Begonia rex Begoniaceae AT
Berberis julianae Berberidaceae As
Berberis microphylla Berberidaceae SAm
Bergenia cordifolia Saxifragaceae As
Beschorneria yuccoides Agavaceae NAm
Betula papyrifera Betulaceae NAm
Betula utilis Betulaceae As
Boronia crenulata Rutaceae Aus
Boswellia carterii Burseraceae Afr
Brachychiton acerifolius Malvaceae Aus
Brachychiton bidwillii Malvaceae Aus
Brachychiton discolor Malvaceae Aus
Brachychiton rupestris Malvaceae Aus
Brachyscome multifida Asteraceae Aus
Brasiliopuntia brasiliensis Cactaceae SAm
Bulbine frutescens Liliaceae Afr
Butia eriospatha Arecaceae SAm
Butia yatai Arecaceae SAm
Buxus microphylla Buxaceae As
Callistemon viminalis Myrtaceae Aus
Callistephus chinensis Asteraceae As
Callitropsis nootkatensis Cupressaceae NAm
Calothamnus quadrifidus Myrtaceae Aus
Camellia japonica Theaceae As
Camellia sasanqua Theaceae As
Campanula carpatica Campanulaceae Eur
Campanula isophylla Campanulaceae Eur
Carex comans Cyperaceae Aus
Carica papaya Caricaceae SAm
Carissa macrocarpa Apocynaceae Afr
Carya illinoinensis Juglandaceae NAm
Caryota maxima Arecaceae Eur
Caryota mitis Arecaceae AT
Caryota urens Arecaceae AT
Casimiroa edulis Rutaceae SAm
Catalpa bungei Bignoniaceae As
Ceanothus integerrimus Rhamnaceae NAm
Ceiba speciosa Malvaceae SAm
Celtis occidentalis Cannabaceae NAm
Cephalocereus senilis Cactaceae NAm
Cercidiphyllum japonicum Cercidiphyllaceae As
Cereus jamacaru Cactaceae SAm
Ceropegia woodii Apocynaceae Afr
Chaenomeles japonica Rosaceae As
Chamaecyparis obtusa Cupressaceae As
Chamaecyparis pisifera Cupressaceae As
Chamaecyparis thyoides Cupressaceae NAm
Chambeyronia macrocarpa Arecaceae Aus
Chamelaucium uncinatum Myrtaceae Aus
Chlorophytum comosum Agavaceae Afr
Choisya ternata Rutaceae NAm
Citronella mucronata Cardiopteridaceae SAm
Citrus limetta Rutaceae As
Citrus medica Rutaceae AT
Citrus reticulata Rutaceae As
Cleistocactus strausii Cactaceae SAm
Cleyera japonica Pentaphylacaceae As
Cocos nucifera Arecaceae Afr, AT, SAm, Pac
Codiaeum variegatum Euphorbiaceae AT
Convolvulus cneorum Convolvulacea Eur, Afr
Copernicia alba Arecaceae SAm
Cordyline fruticosa Asparagaceae AT
Cordyline indivisa Asparagaceae Aus
Coreopsis grandiflora Asteraceae NAm
Cornus controversa Cornaceae As
Cornus forida Cornaceae NAm
Cornus kousa Cornaceae As
Corylus colurna Betulaceae As, Eur
Corylus maxima Betulaceae Eur
Cotoneaster coriaceus Rosaceae AT
Cotoneaster dammeri Rosaceae As
Cotoneaster salicifolius Rosaceae As
Crassula sarcocaulis Crassulaceae Afr
Crotalaria capensis Fabaceae Afr
Cryptocoryne albida Araceae AT
Cryptocoryne parva Araceae AT
Cryptocoryne pygmaea Araceae AT
Cryptocoryne tonkinensis Araceae AT
Cryptocoryne walkeri Araceae AT
Cryptocoryne wendtii Araceae AT
Cryptomeria japonica Cupressaceae As
Cuphea hyssopifolia Lythraceae NAm
Cussonia spicata Araliaceae Afr
Cycas circinalis Cycadaceae AT
Cyclamen persicum Primulaceae Eur
Cyperus papyrus Cyperaceae Afr
Dasylirion lucidum Asparagaceae NAm
Dasylirion serratifolium Asparagaceae NAm
Delosperma congestum Aizoaceae Afr
Dianthus chinensis Caryophyllaceae As
Dieffenbachia seguine Araceae SAm
Dionaea muscipula Droseraceae NAm
Dioon edule Zamiaceae NAm
Dombeya tiliacea Malvaceae Afr
Dracaena braunii Asparagaceae Afr
Dracaena draco Asparagaceae Afr
Dracaena fragans Asparagaceae Afr
Dracaena reflexa Asparagaceae Afr
Drosanthemum speciosum Aizoaceae Afr
Dypsis decaryi Arecaceae Afr
Dypsis decipiens Arecaceae Afr
Dypsis lutescens Arecaceae Afr
Ecchinodorus tenellus Alismataceae NAm
Echinocactus grusonii Cactaceae NAm
Echinocereus nivosus Cactaceae NAm
Echinodorus ozelot Alismataceae NAm
Echinodorus paniculatus Alismataceae NAm
Echinodorus parviflora Alismataceae NAm
Echinodorus tenellus Alismataceae NAm
Echinopsis eyriesii Cactaceae SAm
Echinopsis huascha Cactaceae SAm
Echinopsis macrogona Cactaceae SAm
Egeria najas Hydrocharitaceae SAm
Ensete ventricosum Musaceae Afr
Epipremnum aureum Araceae AT
Erythrina caffra Fabaceae Afr
Erythrina crista-galli Fabaceae SAm
Erythrina falcata Fabaceae SAm
Escallonia macrantha Escalloniaceae SAm
Espostoa guentheri Cactaceae SAm
Espostoa lanata Cactaceae SAm
Eucalyptus coccifera Myrtaceae Aus
Eucalyptus nitens Myrtaceae Aus
Eucalyptus parvifolia Myrtaceae Aus
Eugenia brasiliensis Myrtaceae SAm
Euphorbia abyssinica Euphorbiaceae Afr
Euphorbia avasmontana Euphorbiaceae SAm
Euphorbia baioensis Euphorbiaceae Afr
Euphorbia ingens Euphorbiaceae Afr
Euphorbia martinae Euphorbiaceae Afr
Euphorbia pseudocactus Euphorbiaceae Afr
Euphorbia pulcherrima Euphorbiaceae SAm
Euphorbia trigona Euphorbiaceae Afr
Euryops chrysanthemoides Asteraceae Afr
Euryops pectinatus Asteraceae Afr
Exacum affine Gentianaceae Afr
Fatsia japonica Araliaceae As
Felicia amelloides Asteraceae Afr
Ferocactus emoryi Cactaceae NAm
Ferocactus glaucescens Cactaceae NAm
Ferocactus gracilis Cactaceae NAm
Ferocactus pilosus Cactaceae NAm
Ficus macrophylla Moraceae Aus
Firmiana simplex Malvaceae As, AT
Fissidens fontanus Flissidentaceae NAm
Fontinalis antipyretica Fontanilaceae NAm
Fortunella japonica Rutaceae As
Gazania splendens Asteraceae Afr
Gelsemium sempervirens Gelsemiaceae NAm
Genista lydia Fabaceae Eur
Ginkgo biloba Ginkgoaceae As
Grevillea juniperina Proteaceae Aus
Grevillea lanigera Proteaceae Aus
Griselinia littoralis Griseliniaceae Aus
Hamamelis virginiana Hammamelidaceae NAm
Handroanthus chrysanthus Bignoniaceae SAm
Hardenbergia comptoniana Fabaceae Aus
Haworthia fasciata Xanthorrhoeaceae Afr
Hebe diosmifolia Plantaginaceae Aus
Hebe odora Plantaginaceae Aus
Hebe topiaria Plantaginaceae Aus
Hedera algeriensis Araliaceae Afr
Hedera canariensis Araliaceae Afr
Hottonia inflata Primulaceae NAm
Howea forsteriana Arecaceae Pac
Hoya carnosa Asclepiadaceae AT, Aus
Hydrangea paniculata Hydrangeaceae As
Hydrocotyle tripartita Araliaceae Aus
Impatiens hawkeri Balsaminaceae Aus
Jasminum grandiflorum Oleaceae Afr, AT
Jasminum meznyi Oleaceae As
Jubaea chilensis Arecaceae SAm
Juniperus chinensis Cupressaceae As
Juniperus horizontalis Cupressaceae NAm
Juniperus scopulorum Cupressaceae NAm
Juniperus squamata Cupressaceae As
Justicia brandegeeana Acanthaceae SAm
Kalanchoe beharensis Crassulaceae Afr
Kalanchoe blossfeldiana Crassulaceae Afr
Kerria japonica Rosaceae As
Koelreuteria bipinnata Sapindaceae As
Lampranthus spectabilis Aizoaceae Afr
Leucanthemum paludosum Asteraceae Eur
Leucothoe fontanesiana Ericaceae NAm
Licuala grandis Arecaceae Aus
Ligustrum japonicum Oleaceae As
Liquidambar styraciflua Hammamelidaceae NAm
Liriodendron tulipifera Magnoliaceae NAm
Litchi chinensis Sapindaceae AT
Livistona australis Arecaceae Aus
Lobelia cardinalis Campanulaceae NAm
Lomariopsis lineata Lomaropsidaceae AT, Aus
Lophophora williamsii Cactaceae NAm
Macrozamia communis Cicadaceae Aus
Magnolia denudata Magnoliaceae As
Magnolia grandiflora Magnoliaceae NAm
Magnolia stelllata Magnoliaceae As
Malpighia emarginata Malpighiaceae SAm
Malus floribunda Rosaceae As
Mammillaria geminispina Cactaceae NAm
Mammillaria magnifica Cactaceae NAm
Mammillaria rhodantha Cactaceae NAm
Melaleuca ericifolia Myrtaceae Aus
Melaleuca linearis Myrtaceae Aus
Melocactus neryi Cactaceae SAm
Melocactus zehntneri Cactaceae SAm
Mentha crispata Lamiaceae Cosm
Metasequoia glyptostroboides Taxodiaceae As
Metrosideros excelsa Myrtaceae Aus
Micranthemum callitrichoides Scrophulariaceae SAm
Micranthemum micranthemoides Scrophulariaceae NAm
Micromeria fructicosa Lamiaceae Eur
Microsorum pteropus Polypodiaceae AT
Morus australis Moraceae AT
Musa acuminata Musaceae AT, Aus
Musa basjoo Musaceae As
Myriophyllum mattogrossense Haloragidaceae SAm
Myrtillocactus geometrizans Cactaceae NAm
Nannorrhops ritchieana Arecaceae As
Nasella tenuissima Poaceae SAm
Nemesia strumosa Scrophulariaceae Afr
Nertera granadensis Rubiaceae SAm, Pac
Nolina longifolia Asparagaceae NAm
Nyssa sylvatica Cornaceae NAm
Opuntia macrocentra Cactaceae NAm
Opuntia pubescens Cactaceae SAm
Oreocereus celsianus Cactaceae SAm
Oreocereus doelzianus Cactaceae SAm
Oreocereus leucotrichus Cactaceae SAm
Osmanthus heterophyllus Oleaceae As
Ostrya carpinifolia Betulaceae Eur
Pachira aquatica Bombacaceae SAm
Pachycereus marginatus Cactaceae NAm
Pachycereus pecten-aboriginum Cactaceae NAm
Pachycereus pringlei Cactaceae NAm
Pachypodium lamerei Apocynaceae Afr
Pachysandra terminalis Buxaceae As
Pandanus utilis Pandanaceae Afr
Pandorea jasminoides Bignoniaceae Aus
Panicum virgatum Poaceae NAm
Parajubaea cocoides Arecaceae SAm
Parajubaea torrallyi Arecaceae SAm
Parrotia persica Hamamelidaceae Eur
Passiflora incarnata Passifloraceae SAm
Passiflora manicata Passifloraceae SAm
Pelargonium grandiflorum Geraniaceae Afr
Pellia epiphylla Pelliaceae As, Eur, NAm, Afr
Pennisetum alopecuroides Poaceae As, AT, Aus
Pennisetum messiacum Poaceae Afr
Pennisetum orientale Poaceae Afr, AT
Pentas lanceolata Rubiaceae Afr
Pereskiopsis rotundifolia Cactaceae NAm
Persea americana Lauraceae SAm
Phanera variegata Fabaceae AT
Philodendron bipinnatifidum Araceae SAm
Philodendron tuxtla Araceae SAm
Phlox subulata Polemoniaceae NAm
Phoenix reclinata Arecaceae Afr
Phoenix roebelenii Arecaceae As, AT
Phoenix theophrasti Arecaceae Eur
Phyllostrachys aurea Poaceae As
Picea glauca Pinaceae NAm
Picea koraiensis Pinaceae As
Picea pungens Pinaceae NAm
Pieris japonica Ericaceae As, AT
Pilosocereus leucocephalus Cactaceae NAm
Pilosocereus pachycladus Cactaceae SAm
Pinus brutia Pinaceae Eur
Pinus mugo Pinaceae SAm
Pinus palustris Pinaceae NAm
Pistacia atlantica Anacardiaceae Afr
Pistacía chinensis Anacardiaceae As
Platanus orientalis Platanaceae Eur
Plectranthus verticillatus Lamiaceae Afr
Plumeria alba Apocynaceae SAm
Plumeria rubra Apocynaceae SAm
Polaskia chichipe Cactaceae NAm
Polaskia chula Cactaceae NAm
Polianthes tuberosa Amaryllidaceae SAm
Polygala myrtifolia Polygalaceae Afr
Portulaca umbraticola Portulacaceae NAm
Primula obconica Primulaceae As
Pritchardia hillebrandii Arecaceae Pac
Prunus serrulata Rosaceae As
Prunus subhirtella Rosaceae As
Pseudophoenix sargentii Arecaceae NAm
Pterocarya fraxinifolia Juglandaceae Eur
Puya chilensis Bromeliaceae SAm
Pyrus pyrifolia Rosaceae As
Quercus palustris Fagaceae NAm
Radermachera sinica Bignoniaceae AT
Ranunculus asiaticus Ranunculaceae Eur, Afr
Ravenala madagascariensis Strelitziaceae Afr
Ravenea rivularis Arecaceae Afr
Rhapidophyllum hystrix Arecaceae NAm
Rhapis excelsa Arecaceae As
Rhododendron arboreum Ericaceae AT
Rhododendron molle Ericaceae As
Ribes nigrum Grossulariaceae Eur
Ribes sanguineum Grossulariaceae NAm
Rotala rotundifolia Lythraceae AT
Roystonea regia Arecaceae NAm
Rubus spectabilis Rosaceae NAm
Russelia equisetiformis Scrophulariaceae NAm
Sabal mexicana Arecaceae NAm
Sabal minor Arecaceae NAm
Sabal palmetto Arecaceae NAm
Salix integra Salicaceae As
Salix matsudana Salicaceae As
Sansevieria perrottii Asparagaceae Afr
Schefflera arboricola Araliaceae AT
Scindapsus pictus Araceae AT
Sedum spectabile Crassulaceae As
Selaginella lepidophylla Selaginellaceae NAm
Sequoia sempervirens Cupressaceae NAm
Skimmia japonica Rutaceae As
Sorbus intermedia Rosaceae Eur
Sorbus torminalis Rosaceae Eur, Afr
Staurogyne repens Acanthaceae SAm
Stenocarpus sinuatus Proteaceae Aus
Stephanotis floribunda Apocynaceae Afr
Stetsonia coryne Cactaceae SAm
Stevia rebaudiana Asteraceae SAm
Strelitzia nicolai Stelitziaceae Afr
Strelitzia reginae Stelitziaceae Afr
Syagrus romanzoffiana Arecaceae SAm
Syagrus yungasensis Arecaceae SAm
Symphoricarpos orbiculatus Caprifoliaceae NAm
Taxiphyllum alternans Hypnaceae AT
Taxiphyllum barbieri Hypnaceae AT
Taxodium distichum Taxodiaceae NAm
Tetraclinis articulata Cupressaceae Afr
Thuja occidentalis Cupressaceae NAm
Thuja plicata Cupressaceae NAm
Thymus citriodorus Lamiaceae Cosm
Tilia americana Malvaceae NAm
Tilia tormentosa Malvaceae Eur
Tillandsia flabellata Bromeliaceae SAm
Trachelospermum jasminoides Apocynaceae As, AT
Trachycarpus martianus Arecaceae As
Trithrinax campestris Arecaceae SAm
Ugni molinae Myrtaceae SAm
Utricularia graminifolia Lentibulariaceae AT
Vaccinum macrocarpon Ericaceae NAm
Vallisneria americana Hydrocharitaceae NAm
Vallisneria caulescens Hydrocharitaceae Aus
Veitchia joannis Arecaceae Aus
Vesicularia dubyana Hypnaceae AT
Vesicularia montagnei Hypnaceae AT
Viburnum davidii Adoxaceae As
Viburnum plicatum Adoxaceae As
Viburnum sargentii Adoxaceae As
Vriesea splendens Bromeliaceae SAm
Weigela florida Diervillaceae As
Wodyetia bifurcata Arecaceae Aus
Xerochrysium bracteatum Asteraceae Aus
Yucca elephantipes Agavaceae SAm
Yucca filamentosa Agavaceae NAm
Yucca filifera Agavaceae NAm
Yucca glauca Agavaceae NAm
Yucca rostrata Agavaceae NAm
Zamia furfuracea Zamiaceae NAm
Zamioculcas zamiifolia Araceae Afr
Zelkova carpinifolia Ulmaceae Eur