Australian Tropical Rainforest Plants - Online edition

Senna hirsuta (L.) H.S.Irwin & Barneby

Shrub (woody or herbaceous, 1-6 m tall)
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Leaves and Flowers. © CSIRO
Scale bar 10mm. © CSIRO
Cotyledon stage, epigeal germination. © CSIRO
10th leaf stage. © CSIRO

Irwin, H.S. & Barneby, R.C. (1979) Phytologia 44: 499.

Common name

Woolly Senna; Senna, Woolly


Usually flowers and fruits as a shrub about 2-3 m tall.


Stipules hairy, filiform, about 9-13 mm long, without any obvious venation. Leaflet blades about 40-110 x 15-45 mm, the terminal pair the largest. About eight leaflets per leaf. Twigs, compound leaf rhachis, petioles and leaflets clothed in long pale hairs. Compound leaf rhachis and petiole channelled on the upper surface. A domed gland present on the upper surface of the compound leaf petiole shortly above its junction with the twig. Twigs and leaves emit an obnoxious odour when crushed.


Petals about 14 mm long. Stamens ten, six or more fertile (two large plus four or five smaller) plus three or four staminodes. Ovary villous, hairs white, style glabrous.


Pods pilose, slightly inflated, about 10-14 x 0.4-0.6 cm. Seeds numerous, about 50-90, about 3 x 2 mm. Testa with a dark brown line around the circumference through the hilum.


Cotyledons about 12-19 x 9-11 mm, petiole about 1 mm long. At the tenth leaf stage: compound leaves consist of four leaflets with ciliate margins. Terminal leaflets larger than the lower leaflets. Compound leaf rhachis grooved on the upper surface with a cigar-shaped gland present between the basal pair of leaflets. Leaves emit an unpleasant odour when crushed. Stipules linear, about 2-7 x 0.5 mm long, hairy. Seed germination time 6 to 74 days.

Distribution and Ecology

An introduced species probably from South America but now pantropic. naturalised in NEQ, CEQ and southwards as far as south-eastern Queensland. Altitudinal range in NEQ from near sea level to 800 m. Grows as a roadside weed in rain forest.

Natural History & Notes

Unlikely to be palatable to stock; toxic to rats in laboratory tests. Leaves have been used for medicinal purposes in Java. Hacker (1990).

Cassia hirsuta L., Species Plantarum 2: 378(1753), Type: America, Herb. Cliff. 159, Cassia No 4.
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