Crotalaria retusa
(rattleweed)

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

• Central America: 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

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

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.

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).

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).  

Soil drainage

• free

Soil reaction

• acid
• alkaline
• neutral

Soil texture

• heavy
• light
• medium

Special soil tolerances

• saline
• shallow

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).

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.

• 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

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).