Crotalaria retusa
(rattleweed)

Pictures

Identity

Preferred Scientific Name

• Crotalaria retusa L.

Preferred Common Name

• rattleweed

Other Scientific Names

• Crotalaria cuneifolia (Forssk.) Schrank
• Crotalaria hostmannii Steud.
• Crotalaria retusa var. maritima Trimen
• Crotalaria retusifolia Stokes
• Dolichos cuneifolius Forssk.
• Lupinus cochinchinensis Lour.

International Common Names

• English: devil bean; devil-bean; rattlebox; rattlepod; wedge-leaf crotalaria; wedge-leaf rattlepod
• Spanish: cascabel; cascabelillo; cascabelillo fétido
• French: pistache; pistache marron; pois franc marron
• Chinese: diao qun cao

Local Common Names

• : gallincillo; patillo; quiebra plato
• Bahamas: large yellow rattlebox
• Cambodia: knông sva; kuël
• Colombia: cascabelito
• Cuba: canario; marimena; maromera; maruga
• Dominican Republic: cachimbito; samba; zapatico
• Haiti: pete-pete
• Indonesia: duku todore; orok-orok cina
• Lesser Antilles: jumbie earing; popbush; pwa zombi; shack-shack; shak shak; sonnet; tcha tcha; wild sweet pea; yellow sweet pea
• Madagascar: akondrondolo; akondronjaza; amberivatrincolo
• Malaysia: giring badak
• Philippines: buli-laua; palpaltog; potokan
• Puerto Rico: matraca; sonajuelas
• Venezuela: maraquita

Summary of Invasiveness

Many species in the genus Crotalaria, including the annual herb C. retusa, have been actively introduced in many tropical and subtropical regions of the world to be used in agroforestry systems (Brunner et al., 2013). Evidence available suggests that this species is able to escape from cultivation and naturalize in disturbed areas such as roadsides, waste grounds, urban areas, and grasslands (Wagner et al., 1999; Brunner et al., 2013). Once naturalized this species may become weedy and invasive and has the potential to displace native or desirable vegetation in both natural and managed habitats (ILDIS, 2013; USDA-NRCS, 2013). Currently, C. retusa is classified as a “noxious weed” in 10 states in the United States, Puerto Rico and the Virgin Islands. This species is also listed as invasive in India, Cuba, Cocos Island and several islands in the Pacific Ocean (see distribution table for details; Chandra, 2012; González-Torres et al., 2012; PIER, 2013).

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Fabales
•                         Family: Fabaceae
•                             Subfamily: Faboideae
•                                 Genus: Crotalaria
•                                     Species: Crotalaria retusa

Notes on Taxonomy and Nomenclature

C. retusa is in the subfamily Faboideae (also known as Papilionoideae) of the Fabaceae. Members of this subfamily are trees, shrubs, and herbs that may be easily recognized by their classical pea-shaped flowers and the frequent occurrence of root nodulation (Stevens, 2012).

The genus Crotalaria includes around 700 species, mainly distributed in the Southern Hemisphere throughout tropical regions and extending into the subtropics (Flora of China Editorial Committee, 2012; Roux et al., 2013). This genus has its primary centre of species diversity in tropical and subtropical Africa and Madagascar where approximately 543 species occur, and secondary radiations in temperate Asia, tropical Asia and Australasia with 159 species, South America (mainly in Brazil) with 64 species and North America (Mexico and southern United States) with 34 species (Roux et al., 2013). Crotalaria species are easily recognized by the following combination of characters (Wyk, 2005):

• rostrate keel
• highly inflated fruit
• hairy style
• 5 + 5 anther configuration
• paired callosities on the standard petal
• presence of macrocyclic pyrrolizidine alkaloids

The name ‘rattlebox’ for Crotalaria spp. comes from the sound made when their pod-like fruit is shaken, causing the seeds to “rattle” around inside.

Description

Annual herbs; stems erect, up to 130 cm long, ridged, appressed short-pubescent. Leaves simple, oblanceolate to spatulate, 3-10 × 1-3.8 cm, upper surface glabrous and punctate, lower surface densely sericeous pubescent, apex rounded or retuse, mucronate, base cuneate, petioles 2- 3 mm long, stipules narrowly rhombic-ovate, up to 0.5 mm long. Racemes to 27 cm long, few-flowered, bracts narrowly triangular, minute, early deciduous, calyx broadly bell-shaped, appressed short-pubescent, 12-14 mm long; petals bright yellow, the standard ovate, clawed, to 18 mm long, with reddish veins, wings and keel petals as long as the standard. Pods dark brown to black at maturity, 2.5-4.5 × 1.1-1.3 cm, oblong, nearly cylindrical, glabrous. Seeds approximately 23 per pod, golden-brown to brown, 4-4.5 mm long, smooth (Acevedo-Rodríguez, 1996; Wagner et al., 1999).

Plant Type

Distribution

The exact native distribution range of C. retusa is obscure. At present, this species is considered native to tropical Asia, Africa and Australia and widely naturalized in the tropics (ILDIS, 2013; USDA-ARS, 2013).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

Several Crotalaria species were introduced from Asia into tropical regions in the Western Hemisphere early in the nineteenth century (Sheahan, 2012; USDA-NRCS, 2013). In the West Indies C. retusa was first reported in 1876 in the Virgin Islands (Eggers, 1876). By 1900, this species is listed as a “common herb” in the United States, Mexico, Central America, Brazil, Bahamas, Cuba, Jamaica, Hispaniola, Puerto Rico, Virgin Islands, St Kitts, Guadeloupe, Dominica, Martinique, Netherland Antilles, St Vincent, Barbados, Grenada, and Trinidad and Tobago (Urban, 1905; Orwa et al., 2009).  

Risk of Introduction

C. retusa has been actively introduced to be used as a fibre crop, green manure, forage, ground cover and soil improver, and consequently the risk of new introductions as well as the probability of escape from cultivation is high, mainly in disturbed areas (Wagner et al., 1999; Brunner et al., 2013; PIER, 2013).

Habitat

C. retusa is cultivated in humid tropical areas, but can also grow in semiarid conditions with average annual rainfall as low as 200 mm. C. retusa is common in disturbed areas, roadsides, waste grounds, agricultural lands, pastures, urban areas (i.e., gardens and parks) and grasslands, where it grows as a weed (Wagner et al., 1999; Brunner et al., 2013).

Habitat List

Biology and Ecology

Genetics

The chromosome number reported for C. retusa is 2n=16 (Olivera and Aguiar-Perecin,1999).

Reproductive Biology

Species in the genus Crotalaria are generally reported as self-incompatible. Cross-pollination is extensive and self-pollination occurs only after the stigmatic surface has been stimulated by insects or some other means (Kundu, 1964). Flowers are adapted to buzz-pollination by large bees such as Xylocopa spp. and Vegactile spp (Wyk, 2005).

Physiology and Phenology

C. retusa is an annual herb and its growth is stimulated by high sunlight and water availability (Wagner et al., 1999).

Environmental Requirements

C. retusa grows best in areas with relatively high humidity. However, it is well adapted to drought and can also grow in hot, semiarid habitats (McMullen, 1999). Within its native distribution range, C. retusa occurs in areas with temperatures ranging from 15°C to 27°C. It can tolerate light frosts (-2°C minimum tolerated without injury) and partial salinity conditions (Wagner et al., 1999; Flora of China Editorial Committee, 2012; Brunner et al., 2013; PIER, 2013).

Air Temperature

Rainfall

Rainfall Regime

Soil Tolerances

Soil drainage

• free

Soil reaction

• acid
• alkaline
• neutral

Soil texture

• heavy
• light
• medium

Special soil tolerances

• saline
• shallow

Means of Movement and Dispersal

C. retusa only spreads by seeds. Seeds are ejected short distances from the pods which twist upon drying. Additionally, because plants are common in disturbed and agricultural areas, seeds can be easily dispersed as contaminants in mud or hay adhering to vehicles, humans or livestock (Wagner et al., 1999; Flora of China Editorial Committee, 2012; PIER, 2013).

Pathway Causes

Pathway Vectors

Impact Summary

Economic Impact

C. retusa has escaped from cultivation and become naturalized in disturbed areas, roadsides, waste grounds, urban areas, and grasslands (Wagner et al., 1999; Brunner et al., 2013). Once naturalized, C. retusa grows as a weed and may become invasive, displacing native vegetation (ILDIS, 2013; USDA-NRCS, 2013). In addition, C. retusa is a nitrogen-fixing species and consequently it has the capacity to alter chemical soil conditions, nutrient cycling and trophic levels in invaded ecosystems, with negative effects on native vegetation principally in nutrient-poor ecosystems that did not previously contain nitrogen-fixing plants (Levine et al., 2003). This species is also a noxious weed and annually generates extensive economic impacts principally in agroforestry systems in the United States, West Indies, tropical Asia, and in several islands in the Pacific Ocean (ILDIS, 2013; PIER, 2013; USDA-NRCS, 2013). There are reports of sheep (Nobre et al., 2005; Riet-Correa et al., 2011) and horses (Nobre et al., 2004) being poisoned by C. retusa in Brazil.

Risk and Impact Factors

• Invasive in its native range
• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Highly mobile locally
• Benefits from human association (i.e. it is a human commensal)
• Fast growing

• Altered trophic level
• Damaged ecosystem services
• Ecosystem change/ habitat alteration
• Modification of nutrient regime
• Modification of successional patterns
• Reduced native biodiversity

• Antagonistic (micro-organisms)
• Competition - monopolizing resources
• Pest and disease transmission
• Poisoning
• Rapid growth

• Highly likely to be transported internationally deliberately

Uses

C. retusa is frequently planted in agroforestry system to be used in the production of fibre, forage, and green manure (Brunner et al., 2013). This species is also used as a ground cover and to improve soil condition (ILDIS, 2013; USDA-NRCS, 2013). In Africa, roots are used against coughing up blood. Leaves are used to treat fever, scabies, lung diseases and impetigo. Flowers and leaves are consumed as a vegetable. Roasted seeds are eaten in Vietnam and Africa. Occasionally, Crotalaria retusa is grown as an ornamental, and is used as a dye plant in East Africa (PROTA4U, 2013).

Uses List

Animal feed, fodder, forage

• Fodder/animal feed

Environmental

• Agroforestry
• Erosion control or dune stabilization
• Soil improvement

Human food and beverage

• Seeds
• Vegetable

Materials

• Dyestuffs
• Fibre
• Green manure

Medicinal, pharmaceutical

• Traditional/folklore

Prevention and Control

In small infestations, existing plants of C. retusa should be removed before seeds are produced. Mechanical control should be applied in large infestations and repeated control must be practiced over several years. Glyphosate and triclopyr have been used in the chemical control of several Crotalaria species, but there is no information about chemical control of C. retusa (Cook et al., 2005). Riet-Correa et al. (2011) report that resistant sheep will consume sprouting C. retusa plants, and suggest that they can be used for biological control.

References

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Acevedo-Rodríguez P; Strong MT, 2012. Catalogue of the Seed Plants of the West Indies. Smithsonian Contributions to Botany, 98:1192 pp. Washington DC, USA: Smithsonian Institution. http://botany.si.edu/Antilles/WestIndies/catalog.htm

Broome R; Sabir K; Carrington S, 2007. Plants of the Eastern Caribbean. Online database. Barbados: University of the West Indies. http://ecflora.cavehill.uwi.edu/index.html

Brunner B; Martínez S; Flores L; Morales P, 2013. Crotalaria. Hoja Informativa. Proyecto de Agricultura Orgánica Z-NRCS-007/Z-208 ([English title not available])., Puerto Rico: Estación Experimental Lajas. http://prorganico.info/crotalaria2.pdf

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Nobre VMda T; Riet-Correa F; Barbosa Filho JM; Dantas AFM; Tabosa IM; Vasconcelos JS, 2004. Poisoning by Crotalaria retusa (Fabaceae) in equidae in the semiarid region of Paraíba. (Intoxicação por Crotalaria retusa (Fabaceae) em eqüídeos no semi-árido da Paraíba.) Pesquisa Veterinária Brasileira, 24(3):132-143.

Nobre VMT; Dantas AFM; Riet-Correa F; Barbosa Filho JM; Tabosa IM; Vasconcelos JS, 2005. Acute intoxication by Crotalaria retusa in sheep. Toxicon, 45(3):347-352. http://www.sciencedirect.com/science/journal/00410101

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Links to Websites

Contributors

09/01/14 Original text by:

Julissa Rojas-Sandoval, Department of Botany-Smithsonian NMNH, Washington DC, USA

Pedro Acevedo-Rodríguez, Department of Botany-Smithsonian NMNH, Washington DC, USA

Distribution Maps