United States 

Department of 

Agriculture 

Animal and Plant 

Health Inspection 

Service 

February 13, 2015 

Version 1 

Weed Risk Assessment for Jatropha 

curcas L. (Euphorbiaceae) – Physic 

nut

Top left: Inflorescence of J. curcas. Top right: Seeds and capsule. Bottom left: Habit. 

Bottom right: Leaves and fruit (Source:Starr and Starr, 2009-2012).

Agency Contact: 

Plant Epidemiology and Risk Analysis Laboratory 

Center for Plant Health Science and Technology 

Plant Protection and Quarantine 

Animal and Plant Health Inspection Service 

United States Department of Agriculture 

1730 Varsity Drive, Suite 300 

Raleigh, NC 27606 
Weed Risk Assessment for Jatropha curcas

Ver. 1 February 13, 2015 1

Introduction Plant Protection and Quarantine (PPQ) regulates noxious weeds under the 

authority of the Plant Protection Act (7 U.S.C. § 7701-7786, 2000) and the 

Federal Seed Act (7 U.S.C. § 1581-1610, 1939). A noxious weed is defined as 

“any plant or plant product that can directly or indirectly injure or cause damage 

to crops (including nursery stock or plant products), livestock, poultry, or other 

interests of agriculture, irrigation, navigation, the natural resources of the United 

States, the public health, or the environment” (7 U.S.C. § 7701-7786, 2000). We 

use weed risk assessment (WRA)—specifically, the PPQ WRA model (Koop et 

al., 2012)—to evaluate the risk potential of plants, including those newly 

detected in the United States, those proposed for import, and those emerging as 

weeds elsewhere in the world. 

Because the PPQ WRA model is geographically and climatically neutral, it can 

be used to evaluate the baseline invasive/weed potential of any plant species for 

the entire United States or for any area within it. As part of this analysis, we use 

a stochastic simulation to evaluate how much the uncertainty associated with the 

analysis affects the model outcomes. We also use GIS overlays to evaluate those 

areas of the United States that may be suitable for the establishment of the plant. 

For more information on the PPQ WRA process, please refer to the document, 

Background information on the PPQ Weed Risk Assessment, which is available 

upon request. 

Jatropha curcas L. – Physic nut 

Species Family: Euphorbiaceae 

Information Synonyms: Castiglionia lobata Ruiz & Pav., Curcas adansonii Endl., Cu. 

curcas (L.) Britton & Millsp., C. drastica Mart., C. indica A. Rich., C. 

purgans Medik., Jatropha acerifolia Salisb., J. afrocurcas Pax, J. condor

Wall., J. edulis Cerv., J. moluccana Wall., J. tuberosa Elliot, J. yucatanensis

Briq., Manihot curcas (L.) Crantz, Ricinus americanus Mill., R. jarak Thunb. 

(Tropicos.org, 2014). 

Common names: Physic nut, Barbados nut, curcas bean, purge nut, purging nut 

(Parsons and Cuthbertson, 2001). Known by many other names in different 

languages (see NGRP, 2014; Sunil et al., 2013). 

Botanical description: Jatropha curcas is a deciduous, perennial, somewhat 

succulent, monoecious shrub or small tree that becomes 8 to 15 meters tall 

(Dehgan, 2012; Henning, 2007). Leaves are dark green, ivy-like, smooth, 

heart-shaped, up to 150 mm wide (Parsons and Cuthbertson, 2001). Flowers 

are yellow to green, unisexual, small and inconspicuous (Parsons and 

Cuthbertson, 2001). The inflorescence is a terminal or axillary umbel-like 

cyme, often paired with a solitary female flower terminating each major axis 

and many male flowers on lateral branches (Henning, 2007). It has a yellow 

fruit when immature that turns dark brown when ripe (Orwa et al., 2009; 

Parsons and Cuthbertson, 2001). The fruit is a drupaceous, trilocular, ellipsoid 

capsule, 23 to 30 mm long by 28 mm wide (Dehgan, 2012). The exocarp of 

the fruit remains fleshy until the seeds are mature (Orwa et al., 2009). Seeds 
Weed Risk Assessment for Jatropha curcas

Ver. 1 February 13, 2015 2

are black or black mottled with some white spots, oblong-ellipsoidal, 18 to 20 

mm long by 11 to 13 mm wide, with a smooth seed coat (Dehgan, 2012). 

Refer to Dehgan, 2012) and Reed, 1977) for a detailed botanical description 

of the taxon. 

Initiation: Jatropha curcas is a large shrub being promoted as a biofuel 

feedstock (Carels et al., 2012). On December 23, 2014, the U.S. 

Environmental Protection Agency asked Jonathan Jones, PPQ Noxious 

Weeds Policy Manager, if the invasive potential of Jatropha curcas might 

lead the USDA to recommend additional restrictions on its use as a biofuel 

plant (Lie, 2014). Jones requested that the PERAL Weed Team evaluate this 

species with a weed risk assessment. 

Foreign distribution: Jatropha curcas is native to the American tropics, most 

likely to Mexico, Central America, and the Caribbean (Sunil et al., 2013). It 

has been widely introduced as a hedge and ornamental plant and is widely 

cultivated in tropical and subtropical regions in Africa, Asia, and Latin 

America (GEXSI, 2008; IPCS, 2015; Northern Land Manager, 2011; Parsons 

and Cuthbertson, 2001). 

 U.S. distribution and status: Jatropha curcas is reported in some counties of 

southern Florida (Gann et al., 2001-2014; Kartesz, 2014; NRCS, 2014) and 

“occasionally naturalized” along the east coast of Florida from Brevard 

County southward (Nelson, 2011). It is also “sparsely naturalized” in Hawaii 

(Maui) (Wagner et al., 1990). In Puerto Rico it is “[o]n hillsides, on waste 

grounds and in woodlands, at lower to middle elevations, often planted and 

spontaneous after cultivation” (Liogier and Martorell, 2000). It occurs in 

American Samoa, Guam, Northern Mariana Islands (CABI, 2015), and the 

U.S. Virgin Islands (Más and Lugo-Torres, 2013), but its exact status in those 

territories is unknown. 

 WRA area1

: Entire United States, including territories. 

 

 1. Jatropha curcas analysis 

Establishment/Sprea

d Potential 

Jatropha curcas is a deciduous, perennial plant (Dehgan, 2012; Henning, 2007) 

that produces viable seeds (Brittaine and Lutaladio, 2010). It has been 

introduced as a hedge and ornamental plant and is widely cultivated in tropical 

and subtropical regions in Africa, Asia, and Latin America (GEXSI, 2008; IPCS, 

2015; Northern Land Manager, 2011; Parsons and Cuthbertson, 2001) for 

medicinal purposes (Henning, 2007) and seed oil, which is used for 

manufacturing soap, lamp oil, lubricant, and more recently as a biofuel 

feedstock (Henning, 2007). It is naturalized in many countries (IPCS, 2015; 

Kirtikar, 1903; Maundu and Tengnäs, 2005) and has spread in some others 

(IPCS, 2015). Some mammals, such as rodents, likely disperse seeds of J. 

curcas by moving seeds to their burrows or other feeding sites, but such 

 

1

 “WRA area” is the area in relation to which the weed risk assessment is conducted [definition modified from that for “PRA 

area”] (IPPC, 2012). 
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Ver. 1 February 13, 2015 3

instances are likely rare (Negussie et al., 2014). Jatropha curcas tolerates some 

mutilation by re-sprouting from its tuberous roots when injured (Northern Land 

Manager, 2011; Parsons and Cuthbertson, 2001). We had average uncertainty 

for this risk element. 

Risk score = 7 Uncertainty index = 0.16 

Impact Potential Jatropha curcas is reported as an environmental weed in Australia (Northern 

Land Manager, 2011; University of Queensland, 2011) and in other countries as 

a plant of environmental concern (Space and Flynn, 2002; Space et al., 2009). It 

is a quarantine pest for Australia and South Africa (Brittaine and Lutaladio, 

2010; Parsons and Cuthbertson, 2001). Under laboratory conditions it has been 

shown to be allelopathic (Abugre and Quashie-Sam, 2010; Cremonez et al., 

2013; Ma et al., 2011; Reichel et al., 2013; Rejila and Vijayakumar, 2011; Wang 

et al., 2009), but it is unknown if it has these same effects under field conditions. 

Under some conditions, J. curcas forms thickets that changes habitat structure 

with negative impacts on wildlife (Northern Land Manager, 2011) and it 

apparently threatens biodiversity (University of Queensland, 2011). All parts of 

J. curcas, especially the seeds, are generally toxic to humans and animals 

(Froberg et al., 2007 cited by Ferreira et al., 2011). Animals do not usually eat it, 

however, (IPCS, 2015), and toxicity depends on both plant variety (Brittaine and 

Lutaladio, 2010) and animal species (Ferreira et al., 2011; Heller, 1996; 

University of Queensland, 2011). Although considered a weed of anthropogenic 

and production systems (Holm et al., 1979; Randall, 2007; University of 

Queensland, 2011), we found no evidence that J. curcas is being managed in 

either system. We had very high uncertainty for this risk element due to limited 

detailed accounts of its impacts. 

Risk score = 3 Uncertainty index = 0.29 

Geographic 

Potential 

Based on three climatic variables, we estimate that about 11 percent of the 

United States is suitable for the establishment of J. curcas (Fig. 1). This 

predicted distribution is based on the species’ known distribution elsewhere in 

the world and includes point-referenced localities and areas of occurrence. The 

map for J. curcas represents the joint distribution of Plant Hardiness Zones 9-13, 

areas with 0-100+ inches of annual precipitation, and the following KöppenGeiger climate classes: tropical rainforest, tropical savanna, steppe, desert, 

humid subtropical, and marine west coast. 

The area estimated is likely conservative since it only uses three climatic 

variables. Other environmental variables, such as soil and habitat type, may 

further limit the areas in which this species is likely to establish. Jatropha 

curcas is best adapted to arid and semi-arid conditions (Henning, 2007; Orwa et 

al., 2009). In its native range it is common in deciduous forests and open spaces 

(Dehgan, 2012) and occurs in seasonally dry areas including grassland-savannah 

and thorn forest scrub (Orwa et al., 2009). It also can colonize disturbed areas 

such as railroads, abandoned sites, wastelands, and disturbed sites (CABI, 2015; 

Northern Land Manager, 2011; Parsons and Cuthbertson, 2001). It will grow on 
Weed Risk Assessment for Jatropha curcas

Ver. 1 February 13, 2015 4

degraded, sandy or gravelly, and even saline soils with low nutrient content, but 

cannot survive in waterlogged terrain (Henning, 2007). 

Entry Potential We did not assess the entry potential of J. curcas because it is already present in 

the United States (Kartesz, 2014; Nelson, 2011; Más and Lugo-Torres, 2013; 

NRCS, 2014; Wagner et al., 1990). 

Figure 1. Predicted distribution of Jatropha curcas in the United States. Map 

insets for Alaska, Hawaii, and Puerto Rico are not to scale.

 2. Results 

Model Probabilities: P(Major Invader) = 33.6% 

 P(Minor Invader) = 60.7% 

 P(Non-Invader) = 5.6% 

Risk Result = Evaluate Further 

Secondary Screening = Evaluate Further

 
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Figure 2. Jatropha curcas risk score (black box) relative to the risk scores of 

species used to develop and validate the PPQ WRA model(other symbols). See 

Appendix A for the complete assessment. 

Figure 3. Model simulation results (N=5,000) for uncertainty around the risk 

score for Jatropha curcas. The blue “+” symbol represents the medians of the 

simulated outcomes. The smallest box contains 50 percent of the outcomes, the 

second 95 percent, and the largest 99 percent.
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Ver. 1 February 13, 2015 6

 3. Discussion 

The result of the weed risk assessment for J. curcas is Evaluate Further even 

after secondary screening. This species shares many traits with minor invaders 

(Fig. 2) and our model indicated a 61 percent probability of it being a minor 

invader. The risk score for J. curcas is very near the High Risk threshold 

though, with about 53 percent of the simulated risk scores resulting in a 

determination of High Risk in the uncertainty analysis (Fig. 3). Two different 

evaluations of J. curcas with the Australian Weed Risk Assessment gave this 

plant a reject outcome (Gordon et al., 2011; PIER, 2006). 

The seed oil of this plant is being promoted as a biofuel feedstock (e.g., 

Beckford, n.d.). Consequently, farmers in the United States may be interested in 

growing more of this plant (e.g., Davis, 2011). Areas with tropical climates like 

Hawaii and many U.S. territories are likely to be the most suitable for its 

production as a biofuel (Jongschaap et al., 2007). Jatropha curcas reproduces 

by seed (Henning, 2007) and seed is the product harvested for biofuel feedstock 

oil (Carels et al., 2012). Harvesting J. curcas for biofuel production will 

decrease the number of propagules available, which will reduce the likelihood 

of this plant escaping production fields. In biofuel crops of J. curcas, full 

production is achieved in the fourth or fifth year (Henning, 2007), but under 

ideal conditions, J. curcas can produce seed within the first year (Silip, 2010). If 

not harvested, this seed could contribute to J. curcas escaping from production 

fields. Additionally, J. curcas is a perennial plant with an estimated lifespan of 

30 to 50 years (Henning, 2007); any abandoned groves could serve as a seed 

source for many years. When removing plants, eliminating all of the roots is 

also recommended because re-sprouting can occur (Northern Land Manager, 

2011; Parsons and Cuthbertson, 2001). 

 

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curcas Linn. Journal of Sustainable Development 3(2):291-295. 

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Sujatha, and N. Carels, (eds.). Jatropha, Challenges for a New Energy 

Crop. Volume 2: Genetic Improvement and Biotechnology. Springer 

New York. 

Solomon Raju, A. J., and V. Ezradanam. 2002. Pollination ecology and fruiting 

behavior in a monoecious species, Jatropha curcas L. (Euphorbiaceae). 

Current Science 83(11):1395-1398. 

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invasive plant species of environmental concern. USDA Forest Service, 

Honolulu, HI, U.S.A. 80 pp. 

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Palau: 2008 update on invasive plant species. United States Department 

of Agriculture - Forest Service, Pacific Southwest Research Station, 

Institute of Pacific Islands Forestry, Hilo, Hawai‘i, USA. 233 pp. 

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Environmental. 

http://www.starrenvironmental.com/images/search/?q=Jatropha+curcas&

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New Energy Crop. Volume 2: Genetic Improvement and Biotechnology. 

Springer New York. 

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0605030c0f01/media/Html/Index.htm. (Archived at PERAL). 

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western Indian Ocean: 2. The Comoros Archipelago (Union of the 

Comoros and Mayotte). Forest Health & Biosecurity Working Papers 

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the United Nations, Rome, Italy. 
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Wagner, W. L., D. R. Herbst, and S. H. Sohmer. 1990. Manual of the flowering 

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Honolulu. 

Wang, J. C., Y. Wu, Q. Wang, Y. L. Peng, K. W. Pan, P. Pluo, and N. Wu. 

2009. Allelopathic effects of Jatropha curcas on marigold (Tagetes 

erecta L.). Allelopathy Journal 24(1):123-130. 

Wang, Z. 2012. Chapter 6. Producing Jatropha Biodiesel in China: Policies, 

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Volume 1: Farming, Economics and Biofuel. Springer New York. 

 

 
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Ver. 1 February 13, 2015 13

Appendix A. Weed risk assessment for Jatropha curcas L. (Euphorbiaceae). Below is all of the 

evidence and associated references used to evaluate the risk potential of this taxon. We also include the 

answer, uncertainty rating, and score for each question. The Excel file, where this assessment was 

conducted, is available upon request. 

Question ID Answer - 

Uncertainty 

Score Notes (and references) 

ESTABLISHMENT/SPREAD POTENTIAL 

ES-1 [What is the taxon’s 

establishment and spread status 

outside its native range? (a) 

Introduced elsewhere =>75 years 

ago but not escaped; (b) Introduced 

<75 years ago but not escaped; (c) 

Never moved beyond its native 

range; (d) Escaped/Casual; (e) 

Naturalized; (f) Invasive; (?) 

Unknown] 

e - mod 2 Jatropha curcas is native to the American tropics, most 

likely Mexico and Central America (Sunil et al., 2013). It 

has been introduced to and is widely cultivated in tropical 

and subtropical regions in Africa, Asia, and Latin America 

as a hedge and ornamental plant (GEXSI, 2008; IPCS, 

2015; Northern Land Manager, 2011; Parsons and 

Cuthbertson, 2001). Jatropha curcas has “become 

spontaneous in many countries” where it is cultivated 

(Dehgan, 2012). Is now naturalized in drier areas in many 

African countries (Maundu and Tengnäs, 2005). Jatropha 

curcas “naturalized in bushlands and along rivers in the 

western, central and coastal parts of Kenya” (Maundu and 

Tengnäs, 2005). Naturalized in India (Kirtikar, 1903). It is 

grown occasionally in warmer parts of Australia and is 

naturalized in a few places in Queensland and the Northern 

Territory (IPCS, 2015), and it is now found in the Darwin 

rural area and at Kapalga in Kakadu National Park 

(Northern Land Manager, 2011). Elsewhere, it has been 

reported to colonize disturbed areas along tracks and 

riverbanks (Northern Land Manager, 2011). In the United 

States, “occasionally naturalized” along the east coast of 

Florida (Nelson, 2011). It is also “sparsely naturalized” in 

Hawaii (Maui) (Wagner et al., 1990). In southern Africa, 

the species has spread from Mozambique through Zambia 

to the Transvaal and Natal (IPCS, 2015), this is the only 

evidence supporting spread but we were not able to 

confirm the source. Alternate answers for the Monte Carlo 

simulation are “f” and “d.” 

ES-2 (Is the species highly 

domesticated) 

n - low 0 Jatropha curcas is probably a plant in the process of 

domestication. Jatropha curcas can still be considered a 

(semi-) wild, undomesticated plant showing considerable 

performance variability (Achten et al., 2010). Genetic 

improvement of J. curcas for increasing seed and oil yield 

per unit area is still in its infancy (Divakara et al., 2010). 

Currently, J. curcas breeding and genetic improvement 

programs are carried out for various traits, such as growth 

rate, flowering phenology, and fruit and seed morphology, 

which could potentially increase invasion success 

(Negussie et al., 2013b). Thus we answered no with low 

uncertainty. 

ES-3 (Weedy congeners) y - negl 1 The genus Jatropha contains approximately 170 known 

species (Heller, 1996). A dozen of these are considered 

weeds (Randall, 2012). Jatropha gossypiifolia is regarded 

as an important environmental weed in the Northern 

Territory, Queensland, and the northern parts of Western 

Australia, and is ranked among the top 200 most invasive 

plant species in south-eastern Queensland (University of 

Queensland, 2011). 
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Ver. 1 February 13, 2015 14

Question ID Answer - 

Uncertainty 

Score Notes (and references) 

ES-4 (Shade tolerant at some stage 

of its life cycle) 

n - negl 0 Jatropha curcas is unsuited to growing in shade (Brittaine 

and Lutaladio, 2010). The plant is well adapted to 

conditions of high light intensity (Jongschaap et al., 2007). 

ES-5 (Climbing or smothering 

growth form) 

n - negl 0 Jatropha curcas is neither a vine nor forms tightly 

appressed basal rosettes. Jatropha curcas is an erect shrub 

or small tree with one to several stems that are 2 to 15 

meters tall (Parsons and Cuthbertson, 2001; Dehgan, 

2012). 

ES-6 (Forms dense thickets) y - negl 2 In Australia, Jatropha curcas forms dense thickets or 

colonies (University of Queensland, 2011; Northern Land 

Manager, 2011). In Queensland, Australia, large 

infestations have been reported in a couple of sites, with 

the largest thicket being 100 m long and 50 m wide (Low 

and Booth, 2007). 

ES-7 (Aquatic) n - negl 0 Jatropha curcas is a terrestrial plant. It can grow on 

degraded, sandy or gravelly, and even saline soils with low 

nutrient content, but cannot survive in waterlogged terrain 

(Henning, 2007). 

ES-8 (Grass) n - negl 0 Jatropha curcas is not a grass; it is in the Euphorbiaceae 

family (Dehgan, 2012). 

ES-9 (Nitrogen-fixing woody 

plant) 

n - negl 0 Jatropha curcas is in the Euphorbiaceae, which is not one 

of the families known to contain nitrogen-fixing species 

(Martin and Dowd, 1990; Santi et al., 2013). 

ES-10 (Does it produce viable 

seeds or spores) 

y - negl 1 Jatropha curcas produces viable seeds (Brittaine and 

Lutaladio, 2010; Henning, 2007; University of Queensland, 

2011). 

ES-11 (Self-compatible or 

apomictic) 

y - negl 1 The plants are self-compatible (Juhász et al., 2009). 

ES-12 (Requires special 

pollinators) 

n - negl 0 In India and other parts of the world, many insects are 

reported to effectively pollinate J. curcas (Ovando-Medina 

et al., 2013; Solomon Raju and Bahadur, 2013), including, 

bees, ants, flies and thrips (Solomon Raju and Ezradanam, 

2002). 

ES-13 [What is the taxon’s 

minimum generation time? (a) less 

than a year with multiple 

generations per year; (b) 1 year, 

usually annuals; (c) 2 or 3 years; 

(d) more than 3 years; or (?) 

unknown] 

b - high 1 In a field study conducted in Malaysia, J. curcas took 120 

to 176 days from seeding to dry fruit (Silip, 2010). In 

contrast, J. curcas seed germinates in around 10 days. The 

plant may reach one meter and flower within five months 

under good conditions. Fruit need 90 days from flowering 

until seeds mature (Heller, 1996). Seeds are produced in 

the first or second year of growth (Brittaine and Lutaladio, 

2010). We answered “b.” Alternate answers for the Monte 

Carlo simulation were both “c.” 

ES-14 (Prolific reproduction) n - low -1 Jatropha curcas is a woody shrub or small tree (Parsons 

and Cuthbertson, 2001). Jatropha curcas seed yields are 

highly variable (Heller, 1996; Jingura, 2012). Nevertheless, 

in a survey to characterize seed yields of cultivated J. 

curcas (Wang, 2012), trees with a crown width (or 

diameter) of 4.5 meters produced 1,000 fruits. Each fruit 

normally can have 3 seeds. Based on these data, we 

estimate that J. curcas can produce close to 189 seeds per 

square meter. This was under cultivated conditions and not 

considering seed viability. This information indicates that 

even under the most favorable conditions (e.g., under 
Weed Risk Assessment for Jatropha curcas

Ver. 1 February 13, 2015 15

Question ID Answer - 

Uncertainty 

Score Notes (and references) 

cultivation) J. curcas does not meet the threshold yes 

response for a woody species, which is 1,000 or more 

viable seeds per square meter. 

ES-15 (Propagules likely to be 

dispersed unintentionally by 

people) 

? - max -1 While Parsons and Cuthbertson (2001) state that "longer 

distance [seed] spread is... in mud adhering to...vehicles," 

propagules of J. curcas lack morphological dispersal 

adaptations (i.e., burrs, sticky seeds) that facilitate 

unintentional dispersal by human activity. Seeds of J. 

curcas are smooth coated and relatively large, 18 to 20 mm 

long by 11 to 13 mm wide (Dehgan, 2012). Propagules 

(e.g., seeds) of J. curcas have been intentionally spread by 

humans for cultivations (Brittaine and Lutaladio, 2010; 

Heller, 1996). Thus we answered unknown. 

ES-16 (Propagules likely to 

disperse in trade as contaminants 

or hitchhikers) 

n - mod -1 We found no evidence. 

ES-17 (Number of natural 

dispersal vectors) 

1 -2 Fruit and seed description for ES-17a through ES-17e: The 

fruit is a drupaceous, trilocular, ellipsoid capsule, 23 to 30 

mm long by 28 mm wide, tardily dehiscent (Dehgan, 

2012). The exocarp of the fruit remains fleshy until the 

seeds are mature (Orwa et al., 2009). Seeds are black or 

black mottled with some white spots, oblong-ellipsoidal, 

18 to 20 mm long by 11 to 13 mm wide, with a smooth 

seed coat (Dehgan, 2012). 

 ES-17a (Wind dispersal) n - negl Seeds of J. curcas lack morphological features that would 

facilitate wind dispersal (e.g., Armstrong, 1999). We found 

no evidence that J. curcas propagules are dispersed by 

wind, and it seems unlikely given their size. 

 ES-17b (Water dispersal) n - mod Parson and Cuthbertson (2001) state seeds disperse long 

distances in water flow. We found no further evidence that 

water is a typical means of dispersal. On the contrary, in a 

field study conducted by Negussie et al. (Negussie et al., 

2013a) in Zambia “natural processes such as gravity, water, 

and sediment flows are ineffective vectors for dispersal of 

J. curcas, at least under the studied soil and relatively flat 

slope conditions.” Furthermore, J. curcas is intolerant of 

waterlogged conditions (Brittaine and Lutaladio, 2010). 

Thus we answered no with moderate uncertainty. 

 ES-17c (Bird dispersal) n - high The doves Turtur leucopterus and Chaemaepelia passerine

reportedly eat J. curcas seeds in Jamaica (Gosse, 1847 

cited by Ridley, 1930). However, Ridley (1930) said it is 

doubtful whether the seeds passed through the bird’s 

digestive tract in good enough condition to germinate. We 

answered no, with high uncertainty, because we found no 

additional evidence that seeds of this plant are dispersed by 

birds. 

 ES-17d (Animal external 

dispersal) 

y - high Parsons and Cuthbertson (2001) state that "longer distance 

[seed] spread is... in mud adhering to animal hooves..." In a 

field study in Zambia, Negussie et al. (2013a) discovered 

that toxic J. curcas seeds are frequently dispersed by some 

rodents and shrews. The authors report that these animals 

take the seeds to their burrows, but none germinate due to 

predation or deep burying. Still, some seeds may be 
Weed Risk Assessment for Jatropha curcas

Ver. 1 February 13, 2015 16

Question ID Answer - 

Uncertainty 

Score Notes (and references) 

dropped in route to the burrows or other feeding sites, or 

some may be removed and never eaten. We answered yes, 

with high uncertainty. 

 ES-17e (Animal internal 

dispersal) 

n - low We found no evidence that J. curcas propagules are 

dispersed internally by animals. The large seeds of J curcas

are unlikely to survive mastication. For instance in a field 

study in Zambia, significant amounts of predated J. curcas

seed were found in the burrows of small mammals 

(Negussie et al., 2013a). Furthermore, many animals 

typically do not eat the seed because it is toxic (Heller, 

1996). Thus, its propagules are unlikely to be dispersed 

internally by animals. 

ES-18 (Evidence that a persistent 

(>1yr) propagule bank (seed bank) 

is formed) 

n - mod -1 According to Negussie et al. (2014) no seed dormancy has 

been reported for J. curcas. 

ES-19 (Tolerates/benefits from 

mutilation, cultivation or fire) 

y - low 1 Some suckering occurs from the tuberous roots, 

particularly when plants are injured (Parsons and 

Cuthbertson, 2001). It is recommended that “[i]solated 

plants and small infestations [of J. curcas] should be dug 

out, being careful to remove all of the roots, from which 

the plant can resprout” (Northern Land Manager, 2011). 

ES-20 (Is resistant to some 

herbicides or has the potential to 

become resistant) 

n - low 0 We found no evidence that J. curcas is resistant to 

herbicides. Control recommendations include the use of 

picloram + 2,4-D or picloram + triclopyr mixture in water. 

Also, the use of hexazinone as a soil injection and with 

glyphosate, triclopyr and imazapyr applied as overall 

sprays (Parsons and Cuthbertson, 2001). In a study to 

evaluate the effect of simulated glyphosate drift on the 

initial growth of J. curcas plants under greenhouse 

conditions, plants showed some tolerance to simulated 

glyphosate drift up to a dose of 22.5 g ha-1 (Costa et al., 

2009). However, drift doses above 45.0 g ha-1 of this 

herbicide can severely harm the initial development of J. 

curcas. Furthermore, this species is not listed as an 

herbicide-resistant plant (Heap, 2014). 

ES-21 (Number of cold hardiness 

zones suitable for its survival) 

5 0 

ES-22 (Number of climate types 

suitable for its survival) 

6 2 

ES-23 (Number of precipitation 

bands suitable for its survival) 

11 1 

IMPACT POTENTIAL 

General Impacts 

Imp-G1 (Allelopathic) y - high 0.1 Jatropha curcas produces allelopathic chemicals that 

inhibit the growth of other plants (Abugre and QuashieSam, 2010; Cremonez et al., 2013; Ma et al., 2011; Reichel 

et al., 2013; Rejila and Vijayakumar, 2011; Wang et al., 

2009). We answered yes with high uncertainty because the 

evidence have been derived from studies using artificial 

concentrations of plant tissue extracts and not studies 

derived from field studies under natural conditions. 

Imp-G2 (Parasitic) n - negl 0 We found no evidence that this species is or is not 

parasitic. This species is not a member of a plant family 
Weed Risk Assessment for Jatropha curcas

Ver. 1 February 13, 2015 17

Question ID Answer - 

Uncertainty 

Score Notes (and references) 

known to contain parasitic plant species (Heide-Jorgensen, 

2008; Nickrent, 2012). 

Impacts to Natural Systems 

Imp-N1 (Change ecosystem 

processes and parameters that 

affect other species) 

? - max Unknown. 

Imp-N2 (Change community 

structure) 

y - low 0.2 Jatropha curcas forms thickets that can completely 

transform open woodland or grassland into shrubland, 

making habitat unsuitable for a range of wildlife (Northern 

Land Manager, 2011). If it establishes widespread 

populations, it may threaten some of Australia's rangeland 

communities (University of Queensland, 2011). 

Imp-N3 (Change community 

composition) 

y - low 0.2 Jatropha curcas reportedly threatens biodiversity in the 

Einasleigh and Desert Uplands bioregion in inland northern 

Queensland (University of Queensland, 2011). 

Imp-N4 (Is it likely to affect 

federal Threatened and 

Endangered species) 

y - high 0.1 Jatropha curcas can change habitat structure and alter 

biodiversity (see Imp-N2 and N3), possibly affecting 

Federal Threatened & Endangered (T&E) species. 

Imp-N5 (Is it likely to affect any 

globally outstanding ecoregions) 

n - high We found no evidence J. curcas is likely to negatively 

affect globally outstanding ecoregions. Jatropha curcas is 

reported to invade coastal forest and intermediate-altitude 

forests in the islands of the Comoro Archipelago (Vos, 

2004). In Northern Australia, it occurs in humid and 

subhumid tropical shrublands (Parsons and Cuthbertson, 

2001). It can change habitat structure and threaten 

biodiversity (see Imp-N2 and N3), but we found no 

evidence of it transforming entire ecosystems. Also, J. 

curcas has been present a long time in Florida without 

demonstrating any significant impact (Beckford, n.d.), even 

though the state is part of a globally outstanding ecoregion 

(i.e., Florida Sand Pine Scrub) (Ricketts et al., 1999). 

Imp-N6 [What is the taxon’s weed 

status in natural systems? (a) 

Taxon not a weed; (b) taxon a 

weed but no evidence of control; 

(c) taxon a weed and evidence of 

control efforts] 

c - mod 0.6 Jatropha curcas has invaded coastal forest and 

intermediate-altitude forest in all the islands of the Comoro 

Archipelago (Vos, 2004). It is regarded as an 

environmental weed or potential environmental weed in 

many parts of northern Australia (University of 

Queensland, 2011). It is called a significant environmental 

weed in the Australian Northern Territory Parks and 

Conservation Masterplan. This plant is found in the Darwin 

rural area and at Kapalga in Kakadu National Park. A stand 

at Mount Wells, near Pine Creek, has been eradicated 

(Northern Land Manager, 2011). We answered “c,” with 

moderate uncertainty because we found only one case or no 

further evidence of its control. Alternate answers for the 

Monte Carlo simulation were both “b.” 

Impact to Anthropogenic Systems (cities, suburbs, roadways) 

Imp-A1 (Impacts human property, 

processes, civilization, or safety) 

n - mod 0 We found no evidence. 

Imp-A2 (Changes or limits 

recreational use of an area) 

n - mod 0 We found no evidence. 

Imp-A3 (Outcompetes, replaces, or 

otherwise affects desirable plants 

and vegetation) 

n - mod 0 We found no evidence. 
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Ver. 1 February 13, 2015 18

Question ID Answer - 

Uncertainty 

Score Notes (and references) 

Imp-A4 [What is the taxon’s weed 

status in anthropogenic systems? 

(a) Taxon not a weed; (b) Taxon a 

weed but no evidence of control; 

(c) Taxon a weed and evidence of 

control efforts] 

b - mod 0.1 Jatropha curcas is a weed of tropical and sub-tropical 

environments that is found in disturbed sites, waste areas, 

abandoned gardens and along roadsides (University of 

Queensland, 2011). It colonizes disturbed areas along 

tracks (Northern Land Manager, 2011.) It occurs as relict 

shrubs on abandoned mine and homestead sites (Parsons 

and Cuthbertson, 2001). However, we found no evidence it 

is specifically managed for its impact in these areas. It is 

also widely cultivated (GEXSI, 2008). We answered “b”; 

alternate answers for the Monte Carlo simulation were “a” 

and “c.” 

Impact to Production Systems (agriculture, nurseries, forest plantations, orchards, etc.) 

Imp-P1 (Reduces crop/product 

yield) 

y - high 0.4 In Australia, J. curcas “competes with pasture plants and 

dense thickets may reduce pasture productivity” 

(University of Queensland, 2011). It “may act as an 

alternative host for plant pests, such as the cotton insect 

pest, Caidea dreggi, in Tanzania” (Parsons and 

Cuthbertson, 2001). We found that cultivated J. curcas has 

a number of pests that can be pests of other crops 

(Anonymous, n.d.; Heller, 1996). However, we found no 

evidence that these pests migrate to other crops to cause 

significant issues. 

Imp-P2 (Lowers commodity value) n - mod 0 We found no evidence. 

Imp-P3 (Is it likely to impact trade) n - low 0 Jatropha curcas is a declared noxious weed in Australia’s 

Northern Territory and Western Australia; consequently, it 

is not permitted entry and must be eradicated when found 

in the state (Parsons and Cuthbertson, 2001; University of 

Queensland, 2011). South Africa bans commercial 

production of J. curcas due to environmental concerns 

(Brittaine and Lutaladio, 2010). However, because we 

found no evidence that J. curcas propagules can disperse 

through traded commodities, we answered no. 

Imp-P4 (Reduces the quality or 

availability of irrigation, or 

strongly competes with plants for 

water) 

n - mod 0 We found no evidence. 

Imp-P5 (Toxic to animals, 

including livestock/range animals 

and poultry) 

y - low 0.1 All parts of J. curcas are toxic, especially the seeds, which 

are generally toxic to humans and animals (Froberg et al., 

2007 cited by Ferreira et al., 2011). Varieties commonly 

found growing in Africa and Asia have seeds that are toxic 

to humans and animals, whereas some varieties found in 

Mexico and Central America are known to be non-toxic 

(Brittaine and Lutaladio, 2010). Toxicity has been 

demonstrated on feeding trials with various mammal 

species and chickens, but effects vary by animal species 

(Ferreira et al., 2011; Heller, 1996). It is toxic to livestock, 

though few instances of stock poisoning have been 

reported in Australia (University of Queensland, 2011). 

Jatropha curcas is not usually eaten by animals, but might 

be if drought conditions cause a shortage of forage (IPCS, 

2015). We answered yes, but used low uncertainty because 

while this species is toxic, plants are unlikely to be 

consumed under normal circumstances. 
Weed Risk Assessment for Jatropha curcas

Ver. 1 February 13, 2015 19

Question ID Answer - 

Uncertainty 

Score Notes (and references) 

Imp-P6 [What is the taxon’s weed 

status in production systems? (a) 

Taxon not a weed; (b) Taxon a 

weed but no evidence of control; 

(c) Taxon a weed and evidence of 

control efforts] 

b - mod 0.2 Jatropha curcas is categorized as a weed of agriculture 

(Randall, 2007). In Puerto Rico, it is reported as a 

“common weed” in a crop (Holm et al., 1979). It is also 

reported “present as a weed” in crops in Brazil, Fiji, 

Honduras, India, Jamaica, Panama, and El Salvador, “but 

its rank of importance is unknown” (Holm et al., 1979). 

This species is widely cultivated as a crop in some 

countries of Africa, Asia, and Latin America (GEXSI, 

2008). We answered “b” because we found no evidence 

that it is specifically managed for its impact in crops or 

agriculture. Alternate answers for the Monte Carlo 

simulation were “a” and “c.” 

GEOGRAPHIC POTENTIAL Unless otherwise indicated, the following evidence 

represents geographically referenced points obtained from 

the Global Biodiversity Information Facility (GBIF). 

Plant hardiness zones 

Geo-Z1 (Zone 1) n - negl N/A We found no evidence that it occurs in this zone. 

Geo-Z2 (Zone 2) n - negl N/A We found no evidence that it occurs in this zone. 

Geo-Z3 (Zone 3) n - negl N/A We found no evidence that it occurs in this zone. 

Geo-Z4 (Zone 4) n - negl N/A We found no evidence that it occurs in this zone. 

Geo-Z5 (Zone 5) n - negl N/A We found no evidence that it occurs in this zone. 

Geo-Z6 (Zone 6) n - negl N/A We found no evidence that it occurs in this zone. 

Geo-Z7 (Zone 7) n - mod N/A Although three records exist in China and one in 

Argentina, J. curcas is a tropical and subtropical species 

that is intolerant of frost (Brittaine and Lutaladio, 2010) 

and very low temperatures (<7°C) (Carels et al., 2012). The 

few points we found for Zone 7 may be plants growing in 

protected areas or errors in the maps. Thus, we answered 

no with low uncertainty. 

Geo-Z8 (Zone 8) n - high N/A We found a few points in Mexico and China, but they were 

on the edge of Plant Hardiness Zones 9 and 10. Jatropha 

curcas is a tropical and subtropical plant that is intolerant 

of frost (Brittaine and Lutaladio, 2010) and very low 

temperatures (<7°C) (Carels et al., 2012). The few points 

we found for Zone 8 may be plants growing in protected 

areas or errors in the maps. 

Geo-Z9 (Zone 9) y - negl N/A Mexico, South Africa, China, Argentina, and Bolivia. 

Reported in the United States in Polk County, Florida 

(Kartesz, 2015). 

Geo-Z10 (Zone 10) y - negl N/A Mexico, South Africa, Australia, China, Paraguay, and 

Peru. Reported in the United States in Brevard, Broward, 

Miami Dade, Lee, Manatee and Polk counties in Florida 

(Kartesz, 2015). 

Geo-Z11 (Zone 11) y - negl N/A Mexico, Guatemala, Honduras, Nicaragua, Madagascar, 

Tanzania, Australia, and Peru. Reported in the United 

States in Miami Dade, Lee, and Manatee counties in 

Florida (Kartesz, 2015). 

Geo-Z12 (Zone 12) y - negl N/A Mexico, Guatemala, Honduras, Nicaragua, and Peru. 

Reported in the United States in Miami Dade, Lee, and 

Manatee counties in Florida (Kartesz, 2015). 

Geo-Z13 (Zone 13) y - negl N/A Mexico, Guatemala, Honduras, Nicaragua, the Philippines, 

and Ecuador. Reported in the United States in Maui, Oahu, 
Weed Risk Assessment for Jatropha curcas

Ver. 1 February 13, 2015 20

Question ID Answer - 

Uncertainty 

Score Notes (and references) 

and Niihau in Hawaii (NRCS, 2015; Wagner et al., 1990). 

Köppen -Geiger climate classes 

Geo-C1 (Tropical rainforest) y - negl N/A Nicaragua, Panama, Colombia, Peru, the Philippines, the 

Democratic Republic of Congo, and Brazil. Reported in the 

United States in Hawaii (NRCS, 2015) and in Broward, 

Miami Dade, and Lee counties in Florida (Kartesz, 2015). 

Geo-C2 (Tropical savanna) y - negl N/A Mexico, El Salvador, Honduras, Nicaragua, Ecuador, Peru, 

Brazil, Australia, and Ethiopia. Reported in the United 

States in Maui, Oahu, and Niihau in Hawaii (NRCS, 2015; 

Wagner et al., 1990). 

Geo-C3 (Steppe) y - low N/A Mexico (few), Ecuador, Peru, Madagascar, Tanzania, 

Cameroon, and Australia. 

Geo-C4 (Desert) y - high N/A One point each for Egypt, Yemen, Mauritania, Peru, and 

Ecuador. Grown in Cape Verde (Heller, 1996). Jatropha 

curcas is best adapted to arid and semi-arid conditions. It is 

reported to withstand “years without rainfall in Cape 

Verde" (Heller, 1996). 

Geo-C5 (Mediterranean) n - mod N/A We found one point in Ethiopia, but answered no because 

this plant may be growing in a protected area. 

Geo-C6 (Humid subtropical) y - negl N/A Mexico, South Africa, Australia, and China. Reported in 

the United States in Brevard, Broward, Miami Dade, Lee, 

Manatee, and Polk counties in Florida (NRCS, 2015). 

Geo-C7 (Marine west coast) y - negl N/A Mexico, South Africa, Madagascar, and China. 

Geo-C8 (Humid cont. warm sum.) n - negl N/A We found no evidence that it occurs in this zone. 

Geo-C9 (Humid cont. cool sum.) n - negl N/A We found no evidence that it occurs in this zone. 

Geo-C10 (Subarctic) n - negl N/A We found no evidence that it occurs in this zone. 

Geo-C11 (Tundra) n - negl N/A We found no evidence that it occurs in this zone. 

Geo-C12 (Icecap) n - negl N/A We found no evidence that it occurs in this zone. 

10-inch precipitation bands 

Geo-R1 (0-10 inches; 0-25 cm) y - mod N/A Few points in Peru, Senegal, Egypt, and Mauritania. 

Jatropha curcas is best adapted to arid and semi-arid 

conditions. It is reported to withstand “years without 

rainfall in Cape Verde" (Heller, 1996). 

Geo-R2 (10-20 inches; 25-51 cm) y - negl N/A Mexico, Peru, Mali, Burkina Faso, Senegal, South Africa, 

and the United States in Hawaii (Maui, Oahu, Niihau). 

Geo-R3 (20-30 inches; 51-76 cm) y - negl N/A Mexico, Peru, Bolivia, China, Burkina Faso, Ghana, and 

Tanzania. 

Geo-R4 (30-40 inches; 76-102 cm) y - negl N/A Mexico, Bolivia, Australia, China, and Nigeria. 

Geo-R5 (40-50 inches; 102-127 

cm) 

y - negl N/A Mexico, Bolivia, Australia, China, Paraguay, and the 

United States in Florida (Miami Dade, Lee, Manatee). 

Geo-R6 (50-60 inches; 127-152 

cm) 

y - negl N/A Mexico, Nicaragua, Australia, China, Madagascar, and the 

United States in Florida (Miami Dade, Lee, Manatee). 

Geo-R7 (60-70 inches; 152-178 

cm) 

y - negl N/A Mexico, Nicaragua, China, and the United States in Florida 

(Miami Dade, Lee, Manatee, Polk). 

Geo-R8 (70-80 inches; 178-203 

cm) 

y - negl N/A El Salvador, Nicaragua, China, the Democratic Republic of 

Congo, and in the United States in Florida (Brevard, Miami 

Dade, Polk). 

Geo-R9 (80-90 inches; 203-229 

cm) 

y - negl N/A Nicaragua, Costa Rica, Australia, China, and in the United 

States in Florida (Broward, Miami Dade). 

Geo-R10 (90-100 inches; 229-254 

cm) 

y - negl N/A Mexico, Nicaragua, Costa Rica, Panama, and China, 

Madagascar. 
Weed Risk Assessment for Jatropha curcas

Ver. 1 February 13, 2015 21

Question ID Answer - 

Uncertainty 

Score Notes (and references) 

Geo-R11 (100+ inches; 254+ cm) y - negl N/A Mexico, Nicaragua, Costa Rica, Panama, and China. 

ENTRY POTENTIAL 

Ent-1 (Plant already here) y - negl 1 Jatropha curcas is reported in some counties of southern 

Florida (Kartesz, 2014; NRCS, 2014) and “occasionally 

naturalized” along the east coast of Florida from about 

Brevard County southward (Nelson, 2011). It is also 

“sparsely naturalized” in Hawaii (Maui) (Wagner et al., 

1990). Reported in Puerto Rico and the U.S. Virgin Islands 

(Más and Lugo-Torres, 2013). 

Ent-2 (Plant proposed for entry, or 

entry is imminent ) 

 - N/A 

Ent-3 (Human value & 

cultivation/trade status) 

 - N/A 

Ent-4 (Entry as a contaminant) 

 Ent-4a (Plant present in Canada, 

Mexico, Central America, the 

Caribbean or China ) 

 - N/A 

 Ent-4b (Contaminant of plant 

propagative material (except 

seeds)) 

 - N/A 

 Ent-4c (Contaminant of seeds for 

planting) 

 - N/A 

 Ent-4d (Contaminant of ballast 

water) 

 - N/A 

 Ent-4e (Contaminant of aquarium 

plants or other aquarium products) 

 - N/A 

 Ent-4f (Contaminant of landscape 

products) 

 - N/A 

 Ent-4g (Contaminant of 

containers, packing materials, trade 

goods, equipment or conveyances) 

 - N/A 

 Ent-4h (Contaminants of fruit, 

vegetables, or other products for 

consumption or processing) 

 - N/A 

 Ent-4i (Contaminant of some 

other pathway) 

 - N/A 

Ent-5 (Likely to enter through 

natural dispersal) 

 - N/A