Senna occidentalis (L.) Link

Senna occidentalis (L.) Link

Family

Leguminosae

Synonyms

Cassia occidentalis L., Cassia foetida Persoon, Ditremexa occidentalis (L.) Britton & Rose ex Britton & Wilson.

Vernacular Names

Malaysia

Kachang kota, ketepeng hutan.

English

Negro coffee, coffee senna, stinking weed.

Indonesia

Menting (Javanese), kasingsat (Sundanese), kopi andelan (Sumatra).

Philippines

Balatong-aso (Tagalog), andadasi (Ilokano), duda (Bisaya).

Cambodia

Sanndaek khmaoch.

Laos

Kh'et, lang kh'et.

Thailand

Khilek-thet (Northern), khilek-pi (Central), chumhet-thet (Peninsular).

Vietnam

V[oj]ng giang nam, mu[oof]ng c[oos]t kh[is].

French

Cafe negre, casse-cafe, casse puante.

Geographical Distributions

The origin of Senna occidentalis is unknown; tropical South America and the Old World tropics are thought to be the possible origins. Now, it is a common weed throughout the tropics and subtropics. In Southeast Asia, it occurs everywhere, so if it has been introduced, this must have happened in ancient times. In Indonesia, it is sometimes also cultivated.

Description

Senna occidentalis is an erect, annual or perennial, malodorous, nearly hairless herb that can grow up to 2.5 m tall and with black roots. The stem is obtusely angled or sulcate and often richly branched.

The leaves are arranged spirally and they are pinnately compound. The stipules are triangular to long lance-shaped, more or less falcate and measuring 3-13 cm x 1.5-5 cm. The petiole is 2.5-5.5 cm long, grooved and bearing a large, sessile, nearly ovate, reddish gland at the base that is just above the pulvinus. The rachis is 4-14 cm long with 3-6 pairs of leaflets. The size of leaflets increases from the base to apex of rachis. The leaflet stalk is 2-4 mm long. It is ovate to ovate-oblong, measuring 2.5-17 cm x 1-4 cm, more or less unequal-sided, with rounded base, entire margin, acuminate at apex and the lower surface is pruinose to finely hairy.

The inflorescence is raceme-like, axillary or terminal and 2-4-flowered. The peduncle is 1-7 mm long. The bracts are lance-shaped and measuring 5-18 mm x 1-4.5 mm. The pedicel is 0.5-2 cm long. There are 5 sepals which are unequal and white. The outer ones are orbicular and measure 5-7.5 mm in diametre while the inner ones are ovate and measure 6.5-10 mm long. The 5 petals are obcordate (ventral one), obovate (2 lateral ones) or oblanceolate (2 dorsal ones). The longest is 12-17 mm long, bearing a short claw, yellow and with violet veins. The 10 stamens are unequal in size. The 2 long ones are with filaments 5-7 mm long and anthers 4-7 mm long. The other 4 stamens are with filaments 2-3 mm long and anthers 3-5 mm long, while the remaining 4 are with filaments 3-4 mm long and very small anthers. The pistil is with a hairy ovary, with style 3-5 mm long and small lateral stigma.

The fruit is a flattened-cylindrical legume, measuring 8-13 cm x 0.7-1 cm, straight or slightly incurved, brown with pale margins, nearly smooth and 30-45-seeded.

The seed is flattened-orbicular, measures 3-5 mm in diametre, olive-brown and with an elliptical areole on either side.

Ecology / Cultivation

Senna occidentalis mainly occurs below 500 m, with 1750 m as its altitudinal limit. It grows as a weed in disturbed forest areas, on wastelands, fields, roadsides and around villages and farms. It is especially abundant in ditches and seasonally wet depressions. Although it is resistant to dry conditions, it grows best in a moist environment.

Line Drawing / Photograph

Senna_occidentalis

References

1. Plant Resources of South-East Asia No.16: Stimulants.