Senna occidentalis

Scientific nameSenna occidentalis
PEA FAMILY
Fabaceae; subfamily: Caesalpiniaceae
 
COMMON NAMES
English: ant bush, arsenic bush, coffee senna, sicklepod, stinkweed.
 
DESCRIPTION
Annual or lives for more than one year but less that two, erect herb or shrub (0.5–2.5 m tall); stems reddish-purple, smooth, hairless or sparsely hairy, four-angled or grooved when young becoming greenish-brown and rounded.
Leaves: Green, once-divided (15–20 cm long), with 3–5 pairs of oppositely held egg-shaped or oval leaflets (3–10 cm long and 2–3 cm wide) with broad and rounded bases, tapering towards the end with pointed tips; conspicuous gland at the base of each leaf stalk; alternately held on stems on reddish stalks (3–5 cm long).
Flowers: Bright yellow (20–30 mm across) in small clusters of 2–6 flowers in forks of uppermost leaves.
Fruits: Pods (several-seeded dry fruits that split open at maturity), green turning brown as they mature, flattened, slightly curled (75–130 mm long and 8–10 mm wide), held upright.
 
ORIGIN
Argentina, Belize, Bolivia, Brazil, Cayman Islands, Costa Rica, Dominican Republic, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Haiti, Nicaragua, Panama, Peru, Suriname and Venezuela.
 
REASON FOR INTRODUCTION
Coffee substitute, medicine and ornament.
 
INVADES
Roadsides, wasteland, disturbed land, fallow land, managed pastures, drainage ditches, woodland edges/gaps, savannah, riparian vegetation and gullies.
 
IMPACTS
Dense stands can displace native plant species, and reduce livestock carrying capacities in managed and natural pastures. Being allelopathic, it inhibits the germination and growth of other plants. Studies have shown that it has a negative impact on maize (Arora, 2013) and cotton yields (Higgins et al., 1986), and is an alternative host for crop diseases (Suteri et al., 1979). The seeds of S. occidentalis are highly toxic, containing compounds that damage the liver, the vascular system and the heart and lungs of domestic livestock, often leading to death in cattle (Barros et al., 1999), horses (Riet-Correa et al., 1998), goats (Suliman et al., 1982; Suliman and Shommein, 1986), pigs (Martins et al., 1986), poultry (Haraguchi et al., 1998), and rabbits (O’Hara and Pierce, 1974). Consumption of the seeds in western Uttar Pradesh, in India, resulted in the deaths of nine children within five days (Vashishtha et al., 2007).
 
Source:
Witt, Arne. 2017. Guide to the Naturalized and Invasive Plants of Southeast Asia. CAB International. Retrieved from http://www.cabi.org/cabebooks/ebook/20173158961 on 24 October 2018
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Last updated on 02/14/2019 23:54