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Assessing introduced leguminosae in Mexico to identify potentially high-impact invasive species.

INTRODUCTION

The invasion of natural communities by introduced species is one of the most serious threats to biodiversity and human economic interests, because invasive species displace or replace native species and cause large losses in crop and livestock agroecosystems (Holm et al., 1991; Vitousek et al., 1996; Lonsdale 1999; Lockwood et al., 2001; Vila et al., 2011). Although very few incoming species in a new area become problematic (Williamson and Fitter, 1996), the prediction of which species will be noxious is not yet accurate enough. This occurs in spite of intense research in characteristics of successful invasive species, characteristics of invaded areas, and the interaction among invasive species and invaded environments (Blackburn et al., 2011).

The arrival of exotic species into new territory, intentionally or inadvertently, is by trade and the constant movement of people and plant and animal products (Mack, 1996; Dehnen-Schmutz et al., 2007; von der Lippe and Kowarik, 2008). The risk that an introduced plant can escape, stabilize, and spread, depends on several interacting biological, environmental, and anthropogenic factors that restrict the final number of successful invaders (Wilson et al., 2007). When any exotic plant species establishes, it often takes a long time before it causes a problem ("lag phase"); this period varies from less than 20 years in annuals to over 300 for woody plants (Williamson, 1996; Groves et al., 2005). During the lag phase, evolutionary processes enable the species' following explosive range expansion ("expansive phase") (Williamson, 1996). Problems caused by invasive plants are usually detected at the expansive phase, but at this stage eradication is unviable and only very expensive contention or mitigation actions may be available (Rejmanek and Pitcairn, 2002). Thus, the identification of potentially dangerous introduced plant species becomes imperative besides the identification of exotic species to be excluded from entrance in a new territory. We use "introduced" to refer to exotic species growing without direct human help in natural or managed ecosystems.

Risk assessment models use empirical and theoretically derived criteria that can be useful in assessing introduced species. For example, invasive plant behavior (in the original and introduced ranges) and residence time in the new area, have been used to predict invasions and manage exotic or introduced species (Panetta and Mitchell, 1991; Mack et al., 2000; Meyer, 2000; Rejmanek, 2000; Heger and Trepl, 2003; Essl, 2007; Ricciardi and Cohen, 2007; Wilson et al., 2007; von der Lippe and Kowarik, 2008). In addition, useful exotic species become invasive more easily than non-useful ones, due to assisted propagation, pest protection, and increased propagule pressure (Williamson, 1996). Thus escaped crops, forages, ornamentals, and other horticultural species, account for more than 50% of naturalized species in several parts of the world (Grotkopp et al., 2010). Other important empirical criteria useful in predicting invasions, are unavailable from herbarium based information, for example, seedling growth rate, genome size, minimum generation time, and relative growth rate, among others (Grotkopp et al., 2002; Grotkopp et al., 2010).

Some hypotheses proposed to explain biological invasions can be useful to derive applied criteria in identifying potentially noxious invasive species. The "biotic resistance" proposes that native species in the community resist invasion by occupying all available niches leaving no space for newcomers, thus a negative relationship between native and introduced biodiversity is expected (Elton, 1958; Heger and Trepl, 2003). The "taxonomic affinity" or "phylogenetic repulsion" hypothesis (Mack, 1996; Lockwood et al., 2001; Strauss et al., 2006) predicts that the invasion success of a plant is inversely related with the number of close taxonomic relatives in the community to invade. A practical criterion derived from these hypotheses would be to qualify as more dangerous those exotic species expected to invade low diversity communities and/or those without close relative native species. However, evidence for both hypotheses has been inconclusive, thus they have not used firmly in predicting invasions (Espinosa-Garcia et al., 2004a; Strauss et al., 2006).

Thus, although there are several empirical and theoretical approaches to explain biological invasions, there are practical limitations to predict which species will become noxious (Heger and Trepl, 2003; van Kleunen et al., 2010). This is a problem as efforts to control and/or eradicate exotic species are limited for the many introduced species established in a region, thus priorities have to be set (Randall et al., 2001).

After making an inventory of introduced species, one of the first steps to prioritize their management is to analyze their origin, introduction, distribution, and residence time (Huang et al., 2009; Wu et al., 2003), together with behavior abroad (Randall, 2002). For Mexico, in addition to studies of inventory and distribution patterns of introduced weeds at the national scale (Villasenor and Espinosa-Garcia, 2004; Espinosa-Garcia et al., 2004a; 2004b; 2009), there are very few studies on distribution, abundance or importance for most introduced species the country (Espinosa-Garcia et al., 2009). All those tasks are necessary in accordance with the National Strategy for Invasive Species in Mexico (Anonymous, 2010a). Although national experts identified 23 invasive plant species of potentially high impact to biodiversity in Mexico, they did it without a formal risk analysis (March Mifsut and Martinez Jimenez, 2007). Furthermore, most of the species mentioned in that publication are not present in the country or their presence in Mexico is only suspected. Thus, the risk assessment for more than 600 introduced species in Mexico (Espinosa-Garcia et al., 2009) is pending. However, a full risk analysis (including potential distribution modeling) is a very difficult task for so many species. Thus, in this paper we are proposing a low expert-dependent assessment model to detect the potentially dangerous species to be assessed with a full risk analysis.

The purpose of this paper is to assess introduced legumes in Mexico with empirical and theory-derived criteria to identify potentially high-impact species using herbarium and bibliographic data. The family Leguminosae (s.l.) (Cronquist, 1981) has approximately 650 genera and 18,000 species worldwide; it is one of the most species-rich families in local floras. It occupies the third place with in the global exotic flora after Poaceae and Asteraceae (Pysek, 1998). In Mexico, Leguminosae is the second most important family with 130 genera and approximately 1800 species (Sousa and Delgado, 1993); it also ranks second in importance in the flora of alien weeds with 36 genera and 57 species, representing 9.2% of introduced weeds (Villasenor and Espinosa-Garcia, 2004). This family has contributed the most damaging introduced weeds in Australia (Emms et al., 2005).

We expect that this assessment will serve as a first approach model to indicate the introduced species that require more extensive risk assessments in order to focus eradication, control, containment or mitigation efforts. We used empirical criteria on distribution, residence time, invasive behavior, and usage detailed in the methods sections. We obtained theory-derived criteria testing the hypothesis of phylogenetic repulsion; a negative relationship between native and introduced weed species within the same genus was expected. All species were scored for each criterion. The scoring for criteria was inspired in those used in various weed risk assessment models (e.g. Pheloung, 1999; Koop et al., 2012).

MATERIALS AND METHODS

The analysis was based on the 42 introduced legume species included in the "Malezas Introducidas in Mexico" (MIM) database (Espinosa-Garcia et al., 2000). Twenty-nine introduced legume species added to the introduced flora of Mexico after 2000, and therefore absent in the MIM database, were not included in this analysis (Appendix). We used the records in the MIM database obtained from 1164 specimens in the 11 Mexican herbaria, with the best representation of the flora of Mexico (Table 1).

For each herbarium specimen data were taken on locality (municipality and state), collection date, life form characteristics, and uses. Data were collected on the geographical origin, climatic affinity, and year of its first record in herbarium to estimate residence time for each species. Data not found on the specimens labels were obtained through literature or online searches. We verified the identification of each specimen using reliable botanical descriptions and diagnostic traits obtained from various sources (Espinosa-Garcia et al., 2000)

We used the number of native and introduced weed species within the same genus to determine whether a negative correlation between these groups of weeds occurred as predicted by the phylogenetic repulsion hypothesis. To this end we obtained a list of native weed species in the Leguminosae from the Weed Catalog of Mexico (Villasenor and Espinosa-Garcia, 1998). Native non-weed species were excluded because the disturbed environments colonized by introduced species are those occupied by native weeds. In those environments, native non-weed species are frequently absent and biotic interactions occur mainly between weedy groups (Espinosa-Garcia et al., 2004a).

Criteria for the assessment of introduced species

The evaluation of the naturalized species requires a risk analysis similar to those used to assess the ban on entry of a species to a country. Naturalized species are assessed for current or potential damage to natural or modified ecosystems. The assessment is done through a number of attributes related to their behavior in their places of origin and their introduced ranges; the presence of close relatives in the settled area and the presence invasive close relatives in other parts of the world; its residence time, and the number of localities and habitats occupied in the invaded country. Australians have rating scales for naturalized species according to their importance and current and potential effects on wild and managed ecosystems (Groves et al., 2005). In Mexico, knowledge of the effects of naturalized species is very limited and information is available for very few species (Espinosa-Garcia et al., 2009), making it impossible to apply the Australian scales to assess weeds naturalized in Mexico. Thus, we only used herbarium and literature information as a first approach to prioritize species to avoid potential problems.

Scores were assigned to species according to a) behavior abroad; b) residence time and expected distribution; c) number of habitat types occupied reported in Mexico; d) growth form; e) number of climate types in which it was detected; f) presence of native weeds and invasive relatives within the same genus. Scores for each item were assigned as described below.

For the first criterion, we classified the introduced legumes' behavior in the world according to the World Weed Compendium (Randall, 2002), assigning values for each category: W (Weed) = 0.5; NW (noxious weed) = 1, N (Naturalized) = 0.25, I (Introduced) = 0.25; GE (Garden Escape) = 0.25; EW (Environmental Weed) = 1, EC (Escaped Crop) = 0.25, CI (Casual Invasive) = 0.5.

For the second criterion, we assigned scores according to the magnitude of the residuals of the equation for expected values obtained by correlating residence time and number of localities recorded for all species (Fig. 2b). The rating was calculated according to the deviation of the observed data from the confidence limits of the expected values for each species. The score was 0 if the residuals for the species fell within the confidence limits of the regression line (Fig. 2b). If the residual exceeded the value of the upper confidence limit one to two times, the score was 1; if the residual exceeded two to three times the upper confidence limit, it was 1.5; if the residual exceeded the limit four or more times, the score was 2. For residual values smaller than the lower confidence limit, the score was -1, if the residual was two to three times smaller than the lower confidence limit, the score was -1.5, and if the residual was four or more times smaller than the lower confidence limit, the score was -2.

For the third criterion (habitat breadth), we assigned a value according to the number of habitat types where the species has been recorded. The score was 0 for species recorded in a single habitat type; for species reported in two to four habitat types, 2; the score was 3 if the number of reported habitat types were five to seven, and 3 when they were eight to eleven habitat types. We recognized 11 habitat types: wet areas (WA), disturbed areas (DA), ruderal (R), secondary or disturbed vegetation (SVD), freshwater (FW), shores of salty water (SSW), cropland for annuals (CA), cropland for perennials (CP), natural vegetation (VN), livestock areas (LA) and gardens and meadows (GM). This criterion was based on Bradshaw et al. (2008), who found that in legumes, herbs and vines occupying multiple habitat types were more likely to become invasive.

For the fourth criterion, we assigned values to life forms: 0 for woody perennials (trees and shrubs); 1 for herbaceous plants, and 2 for vines or climbing herbs. Growth habit has been associated with serious damage, mainly with vines or climbing plants (Phillips et al., 2010) or with leguminous trees (Emms et al., 2005).

In the fifth criterion, we assigned 0 to the species occupying areas with one kind of climate and 1 when occupying two or more. We only were able to consider broad climate type categories due to the scarcity or vagueness of climate data on herbarium specimen labels, tropical (A in Koppen's classification), dry (Koppen's B), temperate (Koppen's C), and cold (Koppen's H).

For the sixth criterion we scored -1 for introduced species with close native relatives (within the same genus); a score of 1 to species without close native relatives; 1 for introduced species with introduced relatives, and 0 to introduced species without introduced relatives. These scores were assigned after the analysis performed with introduced and native luminous weeds, where we found patterns (see the results section) mostly consistent with the phylogenetic repulsion hypothesis (Mack, 1991; Lockwood et al., 2001; Strauss et al., 2006).

We correlated the partial sums for criterion groups (behavior abroad, residence time and distribution, and taxonomic affinity) to determine if they were redundant. The species were classified according to the sum of their scores: low-priority attention (L), 1 to 3.5; medium priority (M), 4 to 6.25, and high priority (H), 6.5 to 11.5. The scores for all criteria were based on non-proportional ordinal scales to estimate qualitatively the characteristics used for risk assessment (Randall et al., 2001; Ricciardi and Cohen, 2007).

RESULTS AND DISCUSSION

Introduced legumes are a very diverse group in terms of taxonomic composition, origins, uses and distribution in Mexico (Table 2). The 42 analyzed taxa are distributed in nine genera in three subfamilies: Caesalpinioideae (eigth species); Papilionoideae (31 species and one variety), and Mimosoideae (two species). The leguminous introduced species not considered in this analysis include eight in Caesalpinioideae, 19 in Papilionioideae, and four in Mimosoideae (Appendix). Thus, the subfamily Mimosoideae is strongly underrepresented in the MIM database, as 66.7% of the known introduced species in Mexico for this group were not included there.

Today Mexican herbaria have the best collection of plant specimens collected in Mexico. However, all herbaria, except the Herbario Nacional (MEXU), have information mainly from the 1960's to the present. Although MEXU herbarium was formed with three late nineteenth century herbaria, most specimens in its collection were obtained during and after the 1970's. Mexico's historical collections are in European and United States herbaria; the oldest studied is that of W. Houstoun (with 1731 Veracruz and Campeche specimens), deposited in the British Museum (BM) (Rzedowski et al., 2009). The most complete collection of Mexican plants collected before the 1960's is at the Smithsonian Institution herbarium (US) in Washington. This herbarium has nearly 100,000 Mexican specimens, most of them without duplicates in Mexican institutions. We were not able to revise these foreign herbaria. Therefore, residence times are underestimated, especially for species naturalized in Mexico before 1950; it is difficult to know the degree of underestimation, as many botanists (especially in the first half of the 20th century and before) purposefully ignored weeds or disturbed environments. By the time that "Malezas Introducidas en Mexico" (MIM) database was obtained (Espinosa-Garcia et al., 2000), we estimate that the 11 revised herbaria had more than 2,200,000 specimens, but for 2012, they had more than 2,900,000 (Table 1). Herbaria other than MEXU, which has the best representation of the Mexican flora, were selected for their regional representation, especially when they were located in large agricultural regions or at agronomy universities, e.g. CHAPA, ANSM, UAS (Table 1). Thus, the MIM database is a representative sample of weeds in Mexico.

We will describe and discuss some general features for the analyzed species before we continue to the results and discussion for scoring and evaluation.

Origin

Most analyzed species (95%) come from the Old World (Africa, Asia and Europe), and the rest come from the Americas or Oceania (Tables 1, 2). Most species in the subfamily Papilionoideae originated in the Old World; their herbarium records span are 6 to 100 years old. The Mimosoideae have origins in Oceania and Asia, with early herbarium records from 60 years ago. The Caesalpinoideae come from the Old World and South America, and is the most recently detected subfamily according to their herbarium records (Table 1).

Bibliographic sources sometimes refer to origins in specific continents or regions, and frequently in "the Old World" thus, it is not possible to make a thorough analysis as to the origin of most species. The predominance of Old World species could be explained because during the colonial period Spaniards traded and exchanged plants with Europe and Asia. During this time the main supply bases were the Espanola Island and Cuba, which in turn received commodities from Europe and Africa (Challenger, 1998). The Nao of China was another important way for species introductions from eastern Asia that were transported to New Spain via Acapulco. The Spaniards also introduced livestock, fodder and crops intentionally, and accidentally, plant propagules as stowaways on animals or fodder and as contaminants in crop seeds. Propagules are still introduced accidentally to Mexico in grain and seeds shipments from North America, South America and Europe (Calderon and Espinosa-Garcia, 1997).

Use

All analyzed species have at least one use (Table 2), which suggests that most of them were introduced purposefully into Mexico. The main uses for introduced Caesalpinoideae species are ornamental, medicinal, forage and food (Table 3). Most forage species are in the Papilionoideae (65.6%); ornamentals are in the Mimosoideae (2 species only), Caesalpinoideae (100%) and Papilionoideae (28.1%). Medicinal legumes represent 19.1% and the food species 21.4%. Legumes used as green manure or that are toxic are rare (Table 2. Several species have multiple uses, for example Tamarindus indica, whose fruit pulp is used to make syrups, preserves, juice concentrates, sweets, and sauces. This tree is also ornamental and medicinal; its seeds are used for necklaces, earrings and crafts. Other species such as Arachis hypogaea, Lablab purpureus, Sesbania grandiflora, Spartium junceum, and Vicia faba are also species with more than one use (Table 2).

The usefulness of these plants has probably been important in their introduction, facilitating their establishment and dispersal in the country. They are imported, planted in different places and then these plants escape into the wild (Emms et al., 2005; Huang et al., 2009). In South Africa, introduced ornamentals disseminated faster than introduced species with other uses (Wilson et al., 2007). Another advantage for introduced ornamentals and crops is the continued introduction of new genetic material, hybrid formation and selection of new varieties, which increase the likelihood of adapted local biotypes (Essl, 2007; Wilson et al., 2007). In Britain, the ornamental species introduced by the horticultural industry have had a major impact on the invasions, as they are favored by frequent low prices and high market availability, which translates into a large propagule pressure (Dehnen-Schmutz et al., 2007).

Climate affinity

Introduced legumes in Mexico are mainly from tropical climates. All species of the subfamily Caesalpinoideae and a third of Papilionoideae originated in areas with these climate conditions. Few species in the Mimosoideae and Caesalpinoideae grow in both tropical and temperate climates. The Papilionoideae grow in a wider range of climatic conditions than the other two subfamilies (Anonymous, 1979) (Table 4). The distribution of the introduced legumes in Mexican climatic areas agrees with the homoclimate hypothesis (Panetta and Mitchell, 1991) as species of tropical origin have been registered in tropical areas of Mexico, and those of temperate origin in temperate areas the country (Sanchez-Blanco, 2003).

Taxonomic affinity and the phylogenetic repulsion hypothesis

In Mexico legume weeds are represented by approximately 159 native species (Villasenor and Espinosa-Garcia, 1998) and 72 introduced species (41 in the MIM database and 31 in the appendix). The subfamily of legumes best represented in both introduced and native weeds is Papilionoideae, with 69.4% and 66.7% respectively, followed by Caesalpinoideae (22.2% introduced, 12.6% native) and Mimosoideae (8.3% introduced, 20.7% native). Legume weeds are found in 75 genera in Mexico, including 12 that share native and introduced species (Table 5).

Of the legume genera reported in Mexico, 52% have only native weed species, 32% have introduced weeds only, and those with both types of species represent 16%. The fact that most genera (63) have either native or introduced weeds is consistent with the phylogenetic repulsion hypothesis, which predicts that introduced species success correlates negatively with the presence of related native species. According to this hypothesis, we should expect 100% of the genera have only introduced or native species. Our data indicate that there are 12 genera with both types of species. Even with this number of genera with species of both types, the obtained distribution differs from the null hypothesis in which the expected frequency would be equal proportions for the three genera categories ([chi square] = 19.53, df 2, p <0.0001).

For genera with both types of species, the phylogenetic repulsion hypothesis predicts an inverse relationship between the frequency of native and introduced species in the same genus. There is no detectable pattern in the incidence of native and introduced within the same genus (Spearman rank correlation r = 0.26, p = 0.86). In Crotalaria, Acacia, and Mimosa, native species prevail clearly with a ratio native/ introduced of 3 to 9 (Table 5). In five genera (Caesalpinia, Indigofera, Lathyrus, and Vicia) introduced species prevail over the natives, although in smaller proportions (0.5 to 0.33). Possibly, the number of legume genera with both types of weed species was not large enough to test the phylogenetic repulsion hypothesis adequately. This hypothesis has been tested at the scale habitat or communities. For example, Strauss et al. (2006) found that in California grasslands, the introduced Poaceae species with high ecological impact are phylogenetically more distant to native grasses than the low impact introduced grasses. Another possibility to explain the failed test is that native and introduced species within the same genus are not occurring within the same plant community, a pattern that we could not detect with our data.

Overall, we found that most legume genera either have native or introduced weed species. This is consistent with the phylogenetic repulsion hypothesis and the findings made in floras of different areas of the United States (Mack, 1991; Lockwood et al., 2001; Strauss et al., 2006).

Residence time and distribution

Specimens of introduced Leguminosae in Mexican herbaria date from 1900 to 1993. The year with most first records was 1900 (8 species) and then few records of new species appeared until 1960 (Fig. 1). From the late 1960's to the 1980's there is a steep linear increase in the number of newly detected introduced species, which apparently stopped in 1993. This pattern probably reflects the botanical activity in Mexico more than the species introduction rate. A similar pattern was found in Taiwan, where there were two periods of increased introduced detection (1910-1930 and 1970-2000) with no species detected from 1930 to 1960 (Wu et al., 2003).

Massive plant introductions occurred in Mexico during the colonial period (Challenger, 1998), but we have no precise information on the introduction date for each species. For example, the Spaniards must have introduced many species, deliberately or accidentally, with their cattle, crops and agricultural technology (Challenger, 1998). The species that very likely were introduced in this period are identified in the following residence time analysis. As most of the collections of weeds in Mexico are recent (1950's to present), and foreign herbaria with historical Mexican plant collections were not included in this study, it is likely that residence time and accumulation rate are underestimated, especially for species naturalized in Mexico before the twentieth century.

The 1900 specimens represent forage species or those associated with livestock or crop seeds; they probably were introduced from the sixteenth to eighteenth centuries. Apparently, most ornamental species were introduced after the forage plants in the early 1950. This is consistent with reports by Dehnen-Schmutz et al. (2007) in Britain, where introduced species are mostly ornamental. The pattern of ornamental introduced species accumulation detected from herbarium specimens in South Africa is different from what we found; there, exponential accumulation of the ornamental species occurred around 1840 and probably ended in 1950 (Wilson et al., 2007).

[FIGURE 1 OMITTED]

Very few new legume introduced species were detected in Mexico from 1993 to 2002 (Espinosa-Garcia et al., 2009, Appendix). This contrasts with the pattern found in Australia, where the introduction of species increased 10% per year (Groves et al., 2005). The scarcity of new records in that period could be due to a reduced weed collection, a long time elapsed from specimen collection, to inclusion in herbaria, a very slow new species introduction rate, or all of the above.

The correlation between the number of localities for a species and the years since its first herbarium record is significant (r = 0.39, p = 0.012) (Fig. 2a). This suggests that the earlier the first record, the wider the distribution. However, there are many species outside of the model confidence limits, some with more localities than the expected and vice versa. Most species have residence times of 22 to 47 years and occupy up to 50 localities (Fig. 2a). We suggest that many species with wider distribution than expected most likely were introduced during the colonial period (sixteenth to eighteenth centuries). These early introductions are not documented in herbaria with specimens, and their modern specimen's dates distort the regression analysis. Therefore, we decided to make the residence time analysis only for postcolonial introduced species.

The residence time correlation with the number of localities for species introduced between the 16th and 18th (Table 1) was not significant. Apparently, this group of herbaceous species did not become problematic after more than 200 years of its introduction. This time is much longer than the duration of the noxious invasives lag phase ranging from 20 to 54 years in herbs and from 80 to 300 years trees (Mack, 1981; Kowarick, 1995; Groves, 2006). Invasive neophytes in Spain occupied their potential distribution completely in 143 years on average (Gasso et al., 2010), which is consistent with the 150 years (or possibly twice) estimated in Ireland, Britain Germany and the Czech Republic (Williamson et al., 2009). In tropical climates the lag phase time between introduction and first evidence of dispersion for 23 species in Hawai'i, was 5 years for herbs and 14 years trees (Daehler, 2009).

For the species introduced after the 18th century, the correlation for residence time and number of localities was significant (r = 0.53, p = 0.012) (Fig. 2b). The R2 of this regression model is 0.28, thus, the variation explained by residence time is 28%. This value is not as high as 39 and 44% obtained by Ahern et al. (2010) in Michigan and California, but it is higher than 23% the obtained by Wu et al. (2003).

[FIGURE 2 OMITTED]

The increase in number of localities according to residence time is a well established pattern in plant invasions (Rejmanek and Richardson, 1996). Our results agree with this pattern (Fig. 2b) and those obtained with South African plants (Wilson et al., 2007); with invasive ornamental species in Great Britain (Dehnen-Schmutz et al., 2007), and introduced leguminous species in Taiwan (Wu et al. 2003). However, some introduced legumes in Mexico with short residence times now occur in many states; other species, despite having longer residence time, have been reported in few localities (Fig. 2b). Wilson et al., (2007) and Wu et al. (2003) also reported these kinds of discrepancies.

Species within the confidence limits in the regression with few occupied localities (Fig. 2b), are probably in lag phase (Williamson, 1996; Crooks, 2005); those species could be candidates for successful eradication. The species that could be more worrisome are those expanding faster than expected. However, our data for specific introduced species could be biased by the botanical collection because many botanists have been more interested in collecting native non-weed species than introduced weeds. Thus, instead of focusing in individual species data points, we used the regression model residuals to score the species by estimating their spread rate relative to their residence time.

Priority of attention estimation for introduced leguminous species in Mexico

Priority was estimated by obtaining partial sums for criteria groups (behavior abroad, residence time and distribution, and taxonomic affinity) and then adding these partial sums with the growth habit score (Tables 6, 7, 8). The criteria groups had no significant correlations among them. The total scores sum was obtained for each species (Table 8); then, the species were sorted according to their total to rank each one.

Introduced legumes in Mexico from the MIM database are considered elsewhere in the world (Randall, 2002) as naturalized, 42 (41 species and 1 variety); weed, 41; introduced weed, 26 environmental weed, 21; crop escape, 18; garden escape, 13; invasive casual, 10, and noxious species, 7 (Table 6). The behavior of weeds in other parts of the world has been used as an indicator of the potential behavior of the species in a new area (Rejmanek, 2000); however, the history of the species is not a completely reliable predictor (Rejmanek and Richardson, 1996). Moreover, the behavior of weeds abroad was not correlated with the criterion group of residence time and distribution, indicating that behavior of species abroad might not be a reliable predictor of the introduced Leguminosae behavior in Mexico. Thus, the score sum obtained for the species' behavior abroad, and for the other criterion groups, (Table 8) should be considered more as qualitative indicators more than arithmetic results. We expect that these indicators reflect the ability of the species to invade ecosystems causing economic or environmental damage.

Total scores equal or higher than 6.25 were found for seven species; we suggest that Albizia lebbeck, Pueraria phaseoloides, Lablab purpureus, Securigera varia, Delonix regia, Clitoria ternatea, and Spartium junceum should receive high-priority attention. These species are distributed in more sites than expected by year of introduction, they have been recorded as weeds and environmental weeds in other countries, and occupy up to nine habitat types. Albizia lebbeck, a widespread ornamental, would require increased vigilance because it has been detected as escaped in almost half the country. Another potentially dangerous species is Pueraria phaseoloides because it is a fodder vine and because its relative P. lobata, is causing serious damage in the countries it has invaded (Starr et al., 1999). P. phaseoloides has no native relatives and its use as fodder facilitates its dissemination. Lablab purpureus, Securigera varia (= Coronilla varia), and Clitoria ternatea are potentially dangerous also being vines used as fodder. The most harmful invasive species in Australia were introduced vines (Phillips et al., 2010), because they can spread rapidly and smother native vegetation. According to Humphries et al. (1991) the exotic vines are one of the plant functional groups most destructive in the ecological context. Delonix regia, a common ornamental tree, has been recorded in nine habitat types in Mexico and, aside of having no Mexican relatives, it is considered a weed or environmental weed elsewhere (Table 6). However, its escape into the wild has not been confirmed. The shrub Spartium junceum, considered elsewhere as environmental and noxious weed, was in the high attention group, although it is reported in fewer localities than expected according to its residence time. However, it does not have close relatives in Mexico, and it might be in the lag phase.

Eight species were considered to require medium priority attention because they have been reported as common environmental weeds or weeds. Some of them are distributed in fewer localities than the expected according to their residence time and it is possible that some are in their lag phase. Feral species, ornamental or fodder crops, predominate in this group: Acacia melanoxylon, Alysicarpus vaginalis, Alysicarpus ovalifolius, Crotalaria retusa, Lathyrus latifolius, Lathyrus tingitanus, and Senna didymobotrya. We also classified Bauhinia variegata in this category, despite being known as noxious weed, weed, and relative of environmental weeds because it has 18 non-weed and one weed relatives within the same genus (Torres-Colin, 2006). Thus, it is likely that Bauhinia natural enemies could be attacking B. variegata, preventing it from becoming a problem; Acacia melanoxylon and Crotalaria retusa are probably in the same situation with 11 and 9 native relatives respectively.

We classified seven species as low priority: Cassia javanica, Cercis siliquastrum, Crotalaria pallida, Senna siamea, Sesbania grandiflora, Sutherlandia frutescens, and Vicia villosa. These species are distributed in fewer localities than expected according to residence time and most have native and introduced relatives. We also included Crotalaria pallida in this category although it is distributed in more sites than expected, but it has 11 native weed relatives in the same genus (Villasenor and Espinosa-Garcia, 1998).

The remaining 20 taxa (19 species and 1 variety) were classified in a nonpriority attention category. These species comprise herbaceous feral crops and agricultural weeds probably introduced in the colonial period. Many of them have high total scores in our model, but none has been mentioned as particularly problematic in the more than 200 years residence in Mexico. Indigofera hirsuta and Tamarindus indica, a shrub and a tree respectively, are not regarded as a problem. We have reserves about Cassia fistula being in this group. It is considered environmental weed, it has been recorded in ten habitat types without native relatives and it has harmful relatives elsewhere. All this suggests that Cassia fistula has great plasticity and no biotic barriers, so it could be in a closing lag phase. This species is also a very showy ornamental tree species cultivated in many places, so propagule pressure is high, thereby facilitating its geographic expansion. This Asian ornamental was first recorded by the Royal Botanical Expedition in the New Spain around 1794 (Blanco Fernandez de la Caleya et al., 2010), but it is not clear whether the herbarium specimen was obtained from a feral or cultivated tree. Before we knew about this ancient herbarium record, we classified this species as a high priority of attention species and, if this specimen came from a cultivated tree, Cassia fistula should be considered a high priority species.

Final considerations

The analysis identified species considered noxious or categorized as belonging to the worst weeds in the world, such as Securigera varia, (Williams and Hunyadi, 1987), Albizia lebbeck and Clitoria ternata (Holm et al., 1991), which justified their inclusion in the high priority group. This coincidence suggests that these species, and all the included in the high priority of attention group, should be assessed thoroughly in Mexico, and if necessary, they should be eradicated or contained. It is vital to monitor the dangerous species within and outside their places of origin to take timely management actions (van Kleunen et al., 2010; Ricciardi and Cohen, 2007).

The assessment model presented in this paper still needs further refinement, as seemingly innocuous species scored high and a potentially dangerous species was classified in the non priority category. In both cases the decisive criterion was a very early introduction, thus additional criteria should be developed to prevent false positives or negatives. Still, we hope that the present first-phase introduced assessment model will work as a structured, low expert-dependent approach to identify the introduced species that require a further risk analysis to prioritize efforts for noxious plant management.
APPENDIX

Leguminosae adventive species not included in the analysis performed
in this work. List obtained from Villasenor and Espinosa-Garcia
(2004); Espinosa-Garcia et al. (2009); Blanco Fernandez de la Caleya
et al. (2010); Mario Sousa S1 (personal communication); Williams
(2010) (2); Vibrans (2009) (3).

                                                           Number of
                                                            Mexican
                                                          states with
                                                           herbarium
Species                                   Origin            records

Subfamily Caesalpinioideae
Caesalpinia gilliesii (Hook.) D.
  Dietr.                               South America           8
Caesalpinia pulcherrima (L.) Sw.     Caribbean Islands         26
Ceratonia siliqua L.                     Old World             3
Parkinsonia aculeata L. (1)             Old World,             13
                                      perhaps native
Senna alata (L.) Roxb.                 South America           7
Senna alexandrina Mill.                   Africa               14
Senna spectabilis (DC.) H.S.
  Irwin & Barneby                      South America           6
Senna sulphurea (Collad.) H.S.
   Irwin & Barneby                         Asia                1

Subfamily Papilionioideae
Abrus precatorius L.                     Old World             3
Alhagi camelorum Fisch.                  Old World             1
Canavalia ensiformis (L.) DC.        Caribbean Islands         3
Cicer arietinum L.                       Old World             7
Crotalaria spectabilis Roth. (1)           Asia                4
Crotalaria verrucosa L. (1)                Asia                2
Desmodium barbatum (L.)
  Benth. (1)                           Tropical Asia           10
Desmodium triflorum (L.) DC. (1)       Tropical Asia           12
Indigofera spicata Forssk.               Old World             1
Indigofera tinctoria L.                Tropical Asia           1
Lathyrus odoratus L. (3)                 Old World             1
Lathyrus sphaericus Retz.                Old World             1
Lens culinaris Medik.                    Old World             1
Lespedeza cuneata (Dum. Cours.)
  G. Don                                 Old World             1
Lotus corniculatus L. (2)                Old World             2
Sesbania sesban (L.) Merr.               Old World             1
Stizolobium pruriens (L.)
  Medik. (1)                         Old World tropics         16
Vigna luteola (Jacq.) Benth. (1)          Africa               10
Vigna vexillata (L.) A. Rich. (1)    Old World tropics         7

Subfamily Mimosoideae
Acacia tortuosa (L.) Willd.            Tropical Asia           9
Robiniapseudoacacia L.                 North America           1
Mimosa casta L.                        South America           1
Samanea saman (Jacq.) Merrill       Caribbean Islands,         1
                                      El Salvador to
                                       Colombia and
                                         Venezuela


ACKNOWLEDGEMENTS

We thank to CONABIO U024 project "Malezas introducidas en Mexico" for the full access to the database. We are very grateful to the staff and curators of the herbaria visited during the development of the MIM database. Heberto Ferreira and Alberto Valencia constantly supported us with computer assistance. Nora Sanchez Blanco helped us capture part of the information. This manuscript benefited greatly with the observations and English corrections from an anonymous reviewer and from copy editing from Rosa Maria Murillo. This study was supported by a grant from the Centro de Investigaciones en Ecosistemas, Universidad Nacional Autonoma de Mexico, awarded to Francisco J. Espinosa-Garcia (POFJEG).;

Recibido en febrero de 2012.

Aceptado en mayo de 2012.

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Judith Sanchez-Blanco (1), Clara Sanchez-Blanco (1) *, Mario Sousa S. (2) y Francisco J. Espinosa-Garcia (1,3)

* Part of this work comes from the Bachelor's thesis of C. Sanchez-Blanco that was directed by F.J. Espinosa-Garcia.

(1) Universidad Nacional Autonoma de Mexico, Centro de Investigaciones en Ecosistemas, Antigua Carretera a Patzcuaro 8701, Colonia Ex Hacienda de San Jose de la Huerta, 58089 Morelia, Michoacan, Mexico. (2) Universidad Nacional Autonoma de Mexico, Instituto de Biologia, Departamento de Botanica, Ciudad Universitaria, 04510 Mexico, D.F., Mexico. (3) Author for correspondence: espinosa@oikos.unam.mx
Table 1. Herbaria consulted for the "Malezas Introducidas en Mexico"
(MIM) database (Espinosa-Garcia et al., 2000). The numbers of
specimens included in the third column correspond to different
dates, and they are included just to give an idea of the size of the
collections. Thus, the numbers in the third column do not represent
the size of the collections consulted in 2000 for the MIM database.

Herbarium                      Acronym   Number of specimens

The National herbarium at       MEXU     1,330,000 in 2012; aprox.
the Institute of Biology,                1,000,000 in 2000 (M. Sousa,
Universidad Nacional                     personal comunication, 2012)
Autonoma de Mexico, Mexico
City

National School of              ENCB     1,050,000 in 2012; aprox.
Biological Sciences,                     750,000 in 2000 (R.
Instituto Politecnico                    Fernandez Nava, personal
Nacional, Mexico City                    comunication, 2012)

Institute of Botany (IBUG)      IBUG     130,000 (Davila, 1992)
at the Universidad de
Guadalajara, Guadalajara,
Jalisco

Colegio de Posgraduados in      CHAPA    85,000 (Davila, 1992)
Montecillo, State of Mexico

Center for Scientific           CICY     70,000 (Anonymous, 2010b)
Research of Yucatan, A. C.
(CICY), Merida, Yucatan

Faculty of Sciences of the      FCME     44,000 (Davila, 1992)
Universidad Nacional
Autonoma de Mexico, Mexico
City

Universidad Autonoma Agraria    ANSM     40,000 (Davila, 1992)
Antonio Narro, Saltillo,
Coahuila

Universidad Autonoma de         QMEX     33,000 (Serrano Cardenas,
Queretaro, Santiago de                   2010)
Queretaro, Queretaro

Faculty of Sciences of the      BCMEX    20,000 (Delgadillo, 2008)
Universidad Autonoma de Baja
California, Ensenada, Baja
California

Faculty of Biology of the       EBUM     12,187 (Chavez, 2010)
Universidad Michoacana de
San Nicolas de Hidalgo,
Morelia, Michoacan

College of Agriculture of        UAS     12,000 (Vega Avina, 2000)
the Universidad Autonoma de
Sinaloa, in Culiacan,
Sinaloa

Table 2. List of the assessed adventive Leguminous, origin, usage,
climatic affinity, number of states and municipalities where the
species has been recorded, date for first herbarium record and
growth habit. NA = Not Available.

Species                          Origin            Usage

Subfamily Caesalpinioideae

Bauhinia variegata L.             Asia          Ornamental
(BAUVA)
Cassia fistula L.                 Asia          Ornamental,
(CASFI)                                          medicinal
Cassia javanica L.                Asia          Ornamental,
(CAJAV)                                          medicinal
Cercis siliquastrum L.        Asia, Europe      Ornamental
(CERSI)
Delonix regia (Bojer)            Africa         Ornamental,
Raf. (DELRE)                                     building
Senna didymobotrya               Africa         Ornamental
(Fresen.) Irwin &
Barneby (SENDI)
Senna siamea Lam.                 Asia          Ornamental
(SENSI)
Tamarindus indica L.              Asia             Food,
(TAMIN)                                         ornamental,
                                                 medicinal

Subfamily Papilionioideae
Alysicarpus ovalifolius       Africa, Asia          NA
(Schumach) J. Leonard.
(ALYOV)
Alysicarpus vaginalis             Asia           Forage,
(L.) DC. (ALYVA)                                 medicinal
** Arachis hypogaea L.       South America        Food,
(ARAHY)                       Apparently         medicinal
                              introduced
                               to Mexico
                                 since
                               1300 A.D.
Cajanus cajan (L.)            Africa, Asia      Ornamental,
Millsp. (CAJCA)                                    Food
Clitoria ternatea L.             Africa         Ornamental
(CLITE)
Securigera varia                 Africa         Poisonous,
L.(SECVA)                                       ornamental
Crotalaria pallida Aiton       Old World            ND
(CROPA)
Crotalaria retusa L.           Old World           Food
(CRORE)
Indigofera hirsuta L.          Old World        Sometimes
(INDHI)                                        toxic, forage
Lablab purpureus L.              Africa        Ornamental,
Sweet. (LABPU)                                 food, forage
Lathyrus latifolius L.           Europe         Ornamental
(LATLA)
*** Lathyrus tingitanus          Europe          Forage,
L. (LATIN)                                      ornamental
Medicago lupulina L.          Asia, Europe    Forage, green
(MEDLU)                                           manure
Medicago polymorpha            Old World         Forage,
L. var. polymorpha.                              medicinal
(MEDPVP)
Medicago polymorpha           Asia, Europe        Forage
L. var. vulgaris (Benth)
Shinners (MEDPV)
Medicago sativa L.           Africa, Asia,       Forage,
(MEDSA)                          Europe          medicinal
Melilotus albus Medic.       Asia, Europe,    Forage, green
(MELAL)                      Mediterranean    manure and for
                                 Region            honey
Melilotus indicus (L.)       Mediterranean        Forage
All. (MELIN)                     Region
Melilotus officinalis (L.)    Asia, Europe        Forage
Lam. (MELOF)
Pueraria phaseoloides        Asia, Oceania        Forage
(Roxb.) Benth. (PUEPF)
Pisum sativum L.             Asia, Europe,     Comestible,
(PISSA)                      Mediterranean        forage
                                 Region
Sesbania grandiflora         Asia, Oceania     Ornamental,
(L.) Pers. (SESGRA)                            forage, food
Spartium junceum L.          Mediterranean     Ornamental,
(SPAJU)                          Region          textile,
                                                 medicinal
Sutherlandia frutescens          Africa         Medicinal,
(L.) R. Br. (SUTFRU)                            frnamental
Trifolium dubium Sibth.          Europe           Forage
(TRIDU)
Trifolium pratense L.         Asia, Europe        Forage
(TRIPRA)
Trifolium repens L.           Asia, Europe        Forage
(TRIRE)
Vicia angustifolia L.            Europe           Forage
(VICAN)
Vicia faba L.                Africa, Asia,     Food, green
(VICFA)                      Mediterranean    manure, forage
                                 Region
Vicia sativa L. (VISAT)          Europe           Forage

Vicia villosa Roth.              Europe           Forage
(VICVI)
Vigna unguiculata (L.)            Asia         Forage, food
Walp. (VIGUN)

Subfamily Mimosoideae
Acacia melanoxylon R.           Oceania        Ornamental,
Br. (ACMEL)                                    silvicultural
Albizia lebbeck (L.)              Asia          Ornamental
Benth. (ALBLE)

Species                       Climatic      Number       Number of
                              affinity     of states   municipalities

Subfamily Caesalpinioideae

Bauhinia variegata L.         Tropical,       11             17
(BAUVA)                       temperate
Cassia fistula L.             Tropical         8             13
(CASFI)
Cassia javanica L.            Tropical         1             1
(CAJAV)
Cercis siliquastrum L.        Tropical,        1             1
(CERSI)                       temperate
Delonix regia (Bojer)         Tropical        13             30
Raf. (DELRE)
Senna didymobotrya            Tropical         8             18
(Fresen.) Irwin &
Barneby (SENDI)
Senna siamea Lam.             Tropical         2             4
(SENSI)
Tamarindus indica L.          Tropical        14             36
(TAMIN)

Subfamily Papilionioideae
Alysicarpus ovalifolius       Tropical         1             1
(Schumach) J. Leonard.
(ALYOV)
Alysicarpus vaginalis         Tropical         6             8
(L.) DC. (ALYVA)
** Arachis hypogaea L.        Tropical        10             9
(ARAHY)

Cajanus cajan (L.)            Tropical        13             25
Millsp. (CAJCA)
Clitoria ternatea L.          Tropical        13             20
(CLITE)
Securigera varia              Temperate        1             3
L.(SECVA)
Crotalaria pallida Aiton      Temperate        4             10
(CROPA)
Crotalaria retusa L.         Tropical,        11             26
(CRORE)                       temperate
Indigofera hirsuta L.         Tropical         7             10
(INDHI)
Lablab purpureus L.          Tropical,         9             8
Sweet. (LABPU)                temperate
Lathyrus latifolius L.        Temperate        1             1
(LATLA)
*** Lathyrus tingitanus       Temperate        2             2
L. (LATIN)
Medicago lupulina L.         Tropical,        17             35
(MEDLU)                       temperate
Medicago polymorpha           Temperate       14             31
L. var. polymorpha.
(MEDPVP)
Medicago polymorpha           Temperate       13             25
L. var. vulgaris (Benth)
Shinners (MEDPV)
Medicago sativa L.           Temperate,       21             46
(MEDSA)                          hot
Melilotus albus Medic.       Temperate,       22             28
(MELAL)                          hot

Melilotus indicus (L.)       Temperate,       21             53
All. (MELIN)                     hot
Melilotus officinalis (L.)    Temperate        6             8
Lam. (MELOF)
Pueraria phaseoloides         Tropical         5             8
(Roxb.) Benth. (PUEPF)
Pisum sativum L.             Tropical,         8             10
(PISSA)                       temperate

Sesbania grandiflora          Tropical         2             4
(L.) Pers. (SESGRA)
Spartium junceum L.           Tropical         4             6
(SPAJU)

Sutherlandia frutescens       Tropical         6             9
(L.) R. Br. (SUTFRU)
Trifolium dubium Sibth.      Temperate,        2             3
(TRIDU)                         cold
Trifolium pratense L.        Temperate,        4             6
(TRIPRA)                         hot
Trifolium repens L.          Temperate,       19             31
(TRIRE)                         cold
Vicia angustifolia L.           Cold           1             1
(VICAN)
Vicia faba L.                 Temperate        8             12
(VICFA)

Vicia sativa L. (VISAT)      Temperate,       13             22
                                 hot
Vicia villosa Roth.           Temperate        2             2
(VICVI)
Vigna unguiculata (L.)        Tropical        11             12
Walp. (VIGUN)

Subfamily Mimosoideae
Acacia melanoxylon R.        Tropical,         3             4
Br. (ACMEL)                   temperate
Albizia lebbeck (L.)          Tropical        14             24
Benth. (ALBLE)

Species                         First record        Growth
                              (years to 2000)        habit

Subfamily Caesalpinioideae

Bauhinia variegata L.            1941 (59)           Tree
(BAUVA)
Cassia fistula L.                1753 (247)          Tree
(CASFI)
Cassia javanica L.               1976 (24)           Tree
(CAJAV)
Cercis siliquastrum L.           1963 (37)           Tree
(CERSI)
Delonix regia (Bojer)            1900 (100)          Tree
Raf. (DELRE)
Senna didymobotrya               1971 (29)           Shrub
(Fresen.) Irwin &
Barneby (SENDI)
Senna siamea Lam.                1947 (53)           Tree
(SENSI)
Tamarindus indica L.            1787-1803 *          Tree
(TAMIN)                            (213)

Subfamily Papilionioideae
Alysicarpus ovalifolius          1971 (29)           Herb
(Schumach) J. Leonard.
(ALYOV)
Alysicarpus vaginalis            1955 (45)           Herb
(L.) DC. (ALYVA)
** Arachis hypogaea L.          1900* (100)          Herb
(ARAHY)

Cajanus cajan (L.)           1787-1803 * (213)       Tree
Millsp. (CAJCA)
Clitoria ternatea L.             1961 (39)        Herbaceous
(CLITE)                                              vine
Securigera varia                 1984 (16)        Herbaceous
L.(SECVA)                                            vine
Crotalaria pallida Aiton         1969 (31)           Herb
(CROPA)
Crotalaria retusa L.             1900 (100)          Herb
(CRORE)
Indigofera hirsuta L.           1900 * (100)         Shrub
(INDHI)
Lablab purpureus L.              1966 (34)        Herbaceous
Sweet. (LABPU)                                       vine
Lathyrus latifolius L.           1982 (18)        Herbaceous
(LATLA)                                              vine
*** Lathyrus tingitanus          1986 (14)        Herbaceous
L. (LATIN)                                           vine
Medicago lupulina L.         1787-1803 * (213)       Herb
(MEDLU)
Medicago polymorpha          1787-1803 * (213)       Herb
L. var. polymorpha.
(MEDPVP)
Medicago polymorpha          1787-1803 * (213)       Herb
L. var. vulgaris (Benth)
Shinners (MEDPV)
Medicago sativa L.           1787-1803 * (213)       Herb
(MEDSA)
Melilotus albus Medic.          1964 * (36)          Herb
(MELAL)

Melilotus indicus (L.)          1946 * (54)          Herb
All. (MELIN)
Melilotus officinalis (L.)      1915 * (85)          Herb
Lam. (MELOF)
Pueraria phaseoloides            1977 (23)        Herbaceous
(Roxb.) Benth. (PUEPF)                               vine
Pisum sativum L.             1787-1803 * (213)    Herbaceous
(PISSA)                                              vine

Sesbania grandiflora             1980 (20)           Tree
(L.) Pers. (SESGRA)
Spartium junceum L.              1909 (91)           Shrub
(SPAJU)

Sutherlandia frutescens          1891 (109)          Shrub
(L.) R. Br. (SUTFRU)
Trifolium dubium Sibth.         1973 * (27)          Herb
(TRIDU)
Trifolium pratense L.           1970 * (30)          Herb
(TRIPRA)
Trifolium repens L.             1963 * (37)          Herb
(TRIRE)
Vicia angustifolia L.           1980 * (20)       Herbaceous
(VICAN)                                              vine
Vicia faba L.                   1968 * (32)          Herb
(VICFA)

Vicia sativa L. (VISAT)         1900 * (100)      Herbaceous
                                                     vine
Vicia villosa Roth.             1993 *? (7)       Herbaceous
(VICVI)                                              vine
Vigna unguiculata (L.)          1900 * (100)      Herbaceous
Walp. (VIGUN)                                        vine

Subfamily Mimosoideae
Acacia melanoxylon R.            1956 (44)           Tree
Br. (ACMEL)
Albizia lebbeck (L.)             1947 (53)           Tree
Benth. (ALBLE)

* Species introduced during the colonial period (XVI-XVIII) as crop
or Forage (Challenger, 1998; Blanco Fernandez de la Caleya et al.,
2010). Some of them were probably introduced by accident with
fodder, on livestock or among crop seeds (such as wheat or alfalfa),
as it actually occurs in Mexico (Calderon and Espinosa-Garcia,
1997).

** Arachis hypogaea, archeological evidence for this crop was found
in Tehuacan, Puebla aroundl 1300 A.D. All species in this genus are
of South American origin, thus A. hypogaea was introduced early in
Mexico.

*** Lathyrus tingitanus, apparently was introduced in 1907 as
ornamental; Its escape from cultivation or naturalization date is
not properly recorded as the three herbarium specimens from
apparently wild plants date from 1986.

Table 3. Recorded use for adventive leguminous species in Mexico.
Some species have multiple uses.

                      %                %          % Mimosoideae
               Caesalpinoideae   Papilionoideae        n = 2
Uses                n = 8            n = 32

Food                12.5               25                0
Forage                0               65.6               0
Green manure          0               9.4                0
Medicinal           37.5              15.6               0
Ornamental           100              28.1              100
Other               12.5              6.3               50

               Total %
                n = 42
Uses

Food             21.4
Forage            50
Green manure     7.1
Medicinal        19.1
Ornamental       26.2
Other            9.5

Table 4. Climate of origin of the introduced Leguminosae in Mexico.

Climate                  % Caesalpinoideae     % Papilionoideae
                               n = 8                n = 32

Tropical                         75                  34.4
Temperate                        0                   28.1
Temperate-hot                    0                   15.6
Tropical and temperate           25                  12.5
Temperate-cold                   0                   6.3
Cold                             0                   3.1

Climate                  % Mimosoideae
                             n = 2

Tropical                       50
Temperate                      0
Temperate-hot                  0
Tropical and temperate         50
Temperate-cold                 0
Cold                           0

Table 5. Number of native and adventive species in Leguminous
genera with both types of species.

Subfamily          Genus          Native    Adventive

Caesalpiniaceae    Bauhinia          1          1
Caesalpiniaceae    Caesalpinia       1          2
Caesalpiniaceae    Senna             9          7
Fabaceae           Clitoria          1          1
Fabaceae           Crotalaria        9          3
Fabaceae           Indigofera        1          2
Fabaceae           Lathyrus          1          3
Fabaceae           Sesbania          3          3
Fabaceae           Trifolium         3          3
Fabaceae           Vicia             3          4
Mimosaceae         Acacia           11          2
Mimosaceae         Mimosa            9          1

Table 6. Attributes used to assess Priority of Attention (PA).
Behavior Abroad (BA), obtained from Randall (2002): W = Weed; NW =
Noxious Weed; N = Naturalized; I = Introduced; GE = Garden Escape;
EW = Environmental Weed; CE = Crop Escape; CI = Casual Invasive; SBA
= Score Behavior Abroad; GH = Growth Habit; SGH = Score of Growth
Habit.

                                              BEHAVIOR ABROAD

SPECIES                                W    NW    N      I      GE

Albizia lebbeck                       0.5   1    0.25   0.25   0.25
Pueraria phaseoloides                 0.5   1    0.25    0      0
Lablab purpureus                      0.5   0    0.25    0      0
Securigera varia                      0.5   0    0.25   0.25   0.25
Delonix regia                         0.5   0    0.25    0     0.25
Clitoria ternatea                     0.5   0    0.25   0.25   0.25
Spartium junceum                      0.5   1    0.25   0.25    0
Crotalaria retusa                     0.5   0    0.25    0      0
Acacia melanoxylon                    0.5   1    0.25   0.25   0.25
Bauhinia variegata                    0.5   1    0.25   0.25   0.25
Lathyrus latifolius                   0.5   0    0.25   0.25   0.25
Senna didymobotrya                    0.5   1    0.25   0.25   0.25
Alysicarpus vaginalis                 0.5   0    0.25   0.25    0
Alysicarpus ovalifolius               0.5   0    0.25   0.25    0
Lathyrus tingitanus                   0.5   0    0.25    0      0
Crotalaria pallida                    0.5   0     0      0      0
Sesbania grandiflora                  0.5   0    0.25   0.25    0
Cassia javanica                       0.5   0    0.25    0      0
Sutherlandia frutescens               0.5   0    0.25    0      0
Vicia villosa                         0.5   0    0.25    0      0
Cercis siliquastrum                   0.5   0    0.25   0.25    0
Senna siamea                          0.5   0    0.25   0.25   0.25
Medicago lupulina *                   0.5   1    0.25   0.25    0
Melilotus indicus *                   0.5   0    0.25    0      0
Medicago sativa *                     0.5   0    0.25   0.25   0.25
Cassia fistula *                      0.5   0    0.25   0.25   0.25
Pisum sativum *                       0.5   0    0.25    0      0
Melilotus officinalis *               0.5   0    0.25   0.25    0
Medicago polymorpha var. vulgaris *   0.5   0     0     0.25    0
Melilotus albus *                     0.5   0    0.25    0      0
Trifolium repens *                    0.5   0    0.25   0.25   0.25
Vigna unguiculata *                   0.5   0    0.25   0.25    0
Medicago polymorpha                    0    0    0.25    0      0
var. polymorpha *
Tamarindus indica *                   0.5   0    0.25   0.25    0
Trifolium pratense *                  0.5   0    0.25   0.25   0.25
Cajanus cajan *                       0.5   0    0.25   0.25    0
Arachis hypogaea *                    0.5   0    0.25    0      0
Vicia sativa *                        0.5   0    0.25    0      0
Trifolium dubium *                    0.5   0    0.25   0.25    0
Indigofera hirsuta *                  0.5   0    0.25   0.25    0
Vicia faba *                          0.5   0    0.25   0.25    0
Vicia angustifolia *                  0.5   0     0      0      0

                                          BEHAVIOR ABROAD      GH

SPECIES                               EW    CE    CI    SBA    SGH

Albizia lebbeck                       1    0.25    0    3.5     1
Pueraria phaseoloides                 1    0.25    0     3      2
Lablab purpureus                      1     0     0.5   2.25    2
Securigera varia                      1     0      0    2.25    2
Delonix regia                         1     0      0     2      0
Clitoria ternatea                     1     0      0    2.25    2
Spartium junceum                      1    0.25    0    3.25    0
Crotalaria retusa                           0      0    0.75    1
Acacia melanoxylon                    1    0.25    0    3.5     1
Bauhinia variegata                    1    0.25    0    3.5     0
Lathyrus latifolius                   1    0.25    0    2.5     2
Senna didymobotrya                    0    0.25    0    2.5     0
Alysicarpus vaginalis                 0     0      0     1      1
Alysicarpus ovalifolius               0     0      0     1      1
Lathyrus tingitanus                   1    0.25    0     2      2
Crotalaria pallida                    0     0      0    0.5     1
Sesbania grandiflora                  1     0     0.5   2.5     0
Cassia javanica                       0    0.25    0     1      0
Sutherlandia frutescens               0     0      0    0.75    0
Vicia villosa                         0     0      0    0.75    2
Cercis siliquastrum                   0     0     0.5   1.5     0
Senna siamea                          0     0      0    1.25    0
Medicago lupulina *                   1     0      0     3      1
Melilotus indicus *                   1     0     0.5   2.25    1
Medicago sativa *                     1    0.25   0.5    3      1
Cassia fistula *                      1    0.25    0    2.5     0
Pisum sativum *                       0    0.25   0.5   1.5     2
Melilotus officinalis *               1     0      0     2      1
Medicago polymorpha var. vulgaris *   0     0      0    0.75    1
Melilotus albus *                     0     0      0    0.75    1
Trifolium repens *                    1    0.25    0    2.5     1
Vigna unguiculata *                   0     0     0.5   1.5     2
Medicago polymorpha                   0     0      0    0.25    1
var. polymorpha *
Tamarindus indica *                   1     0      0     2      0
Trifolium pratense *                  1    0.25   0.5    3      1
Cajanus cajan *                       0    0.25   0.5   1.75    0
Arachis hypogaea *                    0     0     0.5   1.25    1
Vicia sativa *                        0    0.25    0     1      0
Trifolium dubium *                    1     0      0     2      1
Indigofera hirsuta *                  0    0.25    0    1.25    0
Vicia faba *                          0    0.25    0    1.25    1
Vicia angustifolia *                  0     0      0    0.5     2

* Residuals for introduced species in the colonial period were not
calculated.

Table 7. Attributes used to assess Priority of Attention (PA).
Residence Time and Distribution (RTD): R = Residuals obtained from
the model shown in Figure 2b; RS= Residuals Score; H = Number of
Occupied Habitats; HS= Habitat Score; C = Number of Climates; SC =
Score for Occupied Climates; TSRTD = Total Score for Residence Time
and distribution. (TA) = Taxonomic affinity; NNWR = Number of Native
Weed Relatives; SNWR = Score for Native Weed Relatives; AWR =
Adventive Weed Relatives; SAWR = Score for Adventive Weed Relatives;
TSTA = Total Score Taxonomic Affinity.

                                         RESIDENCE TIME AND
                                           DISTRIBUTION

SPECIES                        R      RS    H    HS   C    SC    TSRTD

Albizia lebbeck             -27.73     2    9    3    1     0      5
Pueraria phaseoloides       -20.36     0    7    2    1     0      2
Lablab purpureus             -3.52     0    4    1    2     1      2
Securigera varia            -30.87     1    2    1    1     0      2
Delonix regia                25.11     1    9    3    1     0      4
Clitoria ternatea           -18.38     1    7    2    1     0      3
Spartium junceum             49.97     0    7    2    1     0      2
Crotalaria retusa            26.28     1    6    2    2     1      4
Acacia melanoxylon            9.98    -1    2    1    2     1      1
Bauhinia variegata            7.46     0    5    2    2     1      3
Lathyrus latifolius         -12.52     0    2    1    1     0      1
Senna didymobotrya          -29.54     1    7    2    1     0      3
Alysicarpus vaginalis         6.31     0    4    1    1     0      1
Alysicarpus ovalifolius      -0.35    -1    2    1    1     0      0
Lathyrus tingitanus         -15.35     0    1    0    1     0      0
Crotalaria pallida          -15.87     0    6    2    1     0      2
Sesbania grandiflora        -16.36     0    4    1    1     0      1
Cassia javanica              -5.35    -1    2    1    1     0      0
Sutherlandia                 67.97    -1    5    2    1     0      1
frutescens
Vicia villosa               -22.35     0    1    0    1     0      0
Cercis siliquastrum           8.82    -1    1    0    2     1      0
Senna siamea                 16.64    -1    5    2    1     0      1
Medicago lupulina *           --      --    10   3    2     1      4
Melilotus indicus *           --      --    11   3    1     0      3
Medicago sativa *             --      --    7    2    1     0      2
Cassia fistula *              --      --    10   3    1     0      3
Pisum sativum *               --      --    5    2    2     1      3
Melilotus officinalis *       --      --    5    2    1     0      2
Medicago polymorpha           --      --    9    3    1     0      3
var. vulgaris *               --      --
Melilotus albus *             --      --    9    3    1     0      3
Trifolium repens *            --      --    9    3    1     0      3
Vigna unguiculata *           --      --    5    2    1     0      2
Medicago polymorpha           --      --    10   3    1     0      3
var. polymorpha *             --      --
Tamarindus indica *           --      --    8    3    1     0      3
Trifolium pratense *          --      --    6    2    1     0      2
Cajanus cajan *               --      --    9    3    1     0      3
Arachis hypogaea *            --      --    5    2    1     0      2
Vicia sativa *                --      --    5    2    1     0      2
Trifolium dubium *            --      --    2    1    1     0      1
Indigofera hirsuta *          --      --    7    2    1     0      2
Vicia faba *                  --      --    4    1    1     0      1
Vicia angustifolia *          --      --    1    0    1     0      0

                                  TAXONOMIC AFFINITY

SPECIES                     NNWR   SNWR   AWR   SAWR   TSTA

Albizia lebbeck              0       1     1     1       2
Pueraria phaseoloides        0       1     2     1       2
Lablab purpureus             0       1     0     0       1
Securigera varia             0       1     0     0       1
Delonix regia                0       1     0     0       1
Clitoria ternatea            1      -1     0     0      -1
Spartium junceum             0       1     0     0       1
Crotalaria retusa            11     -1     1     1       0
Acacia melanoxylon           11     -1     7     1       0
Bauhinia variegata           19     -1     0     0      -1
Lathyrus latifolius          1      -1     2     1       0
Senna didymobotrya           8      -1     9     1       0
Alysicarpus vaginalis        0       1     1     1       2
Alysicarpus ovalifolius      0       1     1     1       2
Lathyrus tingitanus          1      -1     2     1       0
Crotalaria pallida           11     -1     1     1       0
Sesbania grandiflora         2      -1     4     1       0
Cassia javanica              0       1     2     1       2
Sutherlandia                 0       1     0     0       1
frutescens
Vicia villosa                3      -1     4     1       0
Cercis siliquastrum          0       1     0     0       1
Senna siamea                 8      -1     9     1       2
Medicago lupulina *          0       1     2     1       2
Melilotus indicus *          0       1     1     1       2
Medicago sativa *            0       1     2     1       2
Cassia fistula *             0       1     2     1       2
Pisum sativum *              0       1     0     0       1
Melilotus officinalis *      0       1     1     1       2
Medicago polymorpha          0       1     4     1       2
var. vulgaris *
Melilotus albus *            0       1     2     1       2
Trifolium repens *           3      -1     7     1       0
Vigna unguiculata *          0       1     0     0       1
Medicago polymorpha          0       1     4     1       2
var. polymorpha *
Tamarindus indica *          0       1     0     0       1
Trifolium pratense *         3      -1     7     1       0
Cajanus cajan *              0       1     0     0       1
Arachis hypogaea *           0       1     0     0       1
Vicia sativa *               3      -1     4     1       0
Trifolium dubium *           3      -1     7     1       0
Indigofera hirsuta *         1      -1     1     1       0
Vicia faba *                 3      -1     4     1       0
Vicia angustifolia *         3      -1     4     1       0

* Residuals for introduced species in the colonial period were not
calculated.

Table 8. Attributes used to assess Priority of Attention (PA). TSBA=
Total Score for Behavior Abroad; SGH= Score of Growth Habitat;
TSRTD= Total Score of Residence Time and Distribution; TSTA= Total
Score Taxonomic Affinity. GT=Grand Total. Priority of Attention
(PA): H= High, M= Medium, L= Low, N= Not priority.

SPECIES                    TSBA    SGH    TSRTD    TSTA     GT

Albizia lebbeck             3.5     1       5        2     11.5
Pueraria phaseoloides        3      2       2        2       9
Lablab purpureus           2.25     2       2        1     7.25
Securigera varia           2.25     2       2        1     7.25
Delonix regia                2      0       4        1       7
Clitoria ternatea          2.25     2       3       -1     6.25
Spartium junceum           3.25     0       2        1     6.25
Crotalaria retusa          0.75     1       4        0     5.75
Acacia melanoxylon          3.5     1       1        0      5.5
Bauhinia variegata          3.5     0       3       -1      5.5
Lathyrus latifolius         2.5     2       1        0      5.5
Senna didymobotrya          2.5     0       3        0      5.5
Alysicarpus vaginalis        1      1       1        2       5
Alysicarpus ovalifolius      1      1       0        2       4
Lathyrus tingitanus          2      2       0        0       4
Crotalaria pallida          0.5     1       2        0      3.5
Sesbania grandiflora        2.5     0       1        0      3.5
Cassia javanica              1      0       0        2       3
Sutherlandia frutescens    0.75     0       1        1     2.75
Vicia villosa              0.75     2       0        0     2.75
Cercis siliquastrum         1.5     0       0        1      2.5
Senna siamea               1.25     0       1        0     2.25
Medicago lupulina *          3      1       4        2      10
Melilotus indicus *        2.25     1       3        2     8.25
Medicago sativa *            3      1       2        2       8
Cassia fistula *            2.5     0       3        2      7.5
Pisum sativum *             1.5     2       3        1      7.5
Melilotus officinalis *      2      1       2        2       7
Medicago polymorpha var.   0.75     1       3        2     6.75
vulgaris *
Melilotus albus *          0.75     1       3        2     6.75
Trifolium repens *          2.5     1       3        0      6.5
Vigna unguiculata *         1.5     2       2        1      6.5
Medicago polymorpha var.   0.25     1       3        2     6.25
polymorpha *
Tamarindus indica *          2      0       3        1       6
Trifolium pratense *         3      1       2        0       6
Cajanus cajan *            1.75     0       3        1     5.75
Arachis hypogaea *         1.25     1       2        1     5.25
Vicia sativa *             1.25     2       2        0     5.25
Trifolium dubium *           2      1       1        0       4
Indigofera hirsuta *       1.25     0       2        0     3.25
Vicia faba *               1.25     1       1        0     3.25
Vicia angustifolia *        0.5     2       0        0      2.5

                           Priority of
SPECIES                     attention

Albizia lebbeck                 H
Pueraria phaseoloides           H
Lablab purpureus                H
Securigera varia                H
Delonix regia                   H
Clitoria ternatea               H
Spartium junceum                H
Crotalaria retusa               M
Acacia melanoxylon              M
Bauhinia variegata              M
Lathyrus latifolius             M
Senna didymobotrya              M
Alysicarpus vaginalis           M
Alysicarpus ovalifolius         M
Lathyrus tingitanus             M
Crotalaria pallida              L
Sesbania grandiflora            L
Cassia javanica                 L
Sutherlandia frutescens         L
Vicia villosa                   L
Cercis siliquastrum             L
Senna siamea                    L
Medicago lupulina *             N
Melilotus indicus *             N
Medicago sativa *               N
Cassia fistula *                N
Pisum sativum *                 N
Melilotus officinalis *         N
Medicago polymorpha var.        N
vulgaris *
Melilotus albus *               N
Trifolium repens *              N
Vigna unguiculata *             N
Medicago polymorpha var.        N
polymorpha *
Tamarindus indica *             N
Trifolium pratense *            N
Cajanus cajan *                 N
Arachis hypogaea *              N
Vicia sativa *                  N
Trifolium dubium *              N
Indigofera hirsuta *            N
Vicia faba *                    N
Vicia angustifolia *            N

* Residuals for introduced species in the colonial period were not
calculated.
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Author:Sanchez-Blanco, Judith; Sanchez-Blanco, Clara; Sousa S., Mario; Espinosa-Garcia, Francisco J.
Publication:Acta Botanica Mexicana
Date:Jul 1, 2012
Words:12959
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