Author: (Burmann f.) Irwin & Barneby
Morphological description (surattensis Senna compl FT29 )
Shrub or small tree up to 7 m tall; young branches puberulous. Stipules linear falcate, 5-10 mm long, subpersistent.
Leaves paripinnate with 6-9 pairs of leaflets; petioles 1.5-3 cm; rachis up to 15 cm with a clavate, 1-2 mm long gland between the 2-3 lower pairs of leaflets. Leaflets with short petiolule, ovate to ovate-oblong, 2.5-4 by 1-1.7 cm; upper surface glabrous, lower sparsely pubescent; apex rounded, more or less slightly emarginate, base rounded, rarely cuneate.
Inflorescence: (surattensis Senna compl 386527; surattensis Senna infl JRN5-28) Racemes from the upper leaf axils, 3-6 cm long, 10-15-flowered; peduncle 2.5-5 cm; bracts ovate acute, 4-5 mm long, finally reflexed; bracteoles absent; pedicels 1-2 cm.
Flower: (surattensis Senna compl FT29 )Sepals 5: 2 outer more or less orbicular, c. 3 mm long; 3 inner obovate up to 7 mm long. Petals yellow, subequal, ovate-obovate, 1.5-2 cm long with a 1-1.5 mm long, narrow claw. Stamens 10 fertile, with straight, short, thick filaments, 1-4 mm long; anthers subequal, 5-7 mm long, opening by apical slits. Ovary puberulous; style glabrous; stigma indistinct.
Pods flat, glabrous with papery valves, 7-10 by 1-1.5 cm (surattensis Senna pods Valkenb2 ).
Seeds 15-25, glossy flattened, 8 by 4 mm.
Distribution
Origin uncertain. Irwin & Barneby (1982: 81) quote Bentham who thought it native of N Australia, while later authors regard it as introduced there. It might come from the same area in India as the closely related Senna sulfurea , but it seems mainly, also here, to be a garden plant. It is also widely cultivated in the Neotropics.
Habitat
It seems to have a wide ecological amplitude. It is naturalized widely in the Indo-Malesian region in open, disturbed forests, waste places and around villages.