Alternative common names:
Shower tree senna, sicklepod, slimpod glaberrima senna, stinking cassia.
Hairy senna is a large, upright plant with deep orange-yellow irregular flowers. The stems and leaves are covered with long, pale greyish-white hairs. The leaflets are egg-shaped and the fruit is slightly sickle-shaped. The seeds are olive or brown.
Where does this species come from?Southern USA, Mexico, Central America and subtropical South America.
What is its invasive status in South Africa?NEMBA 2020 Category 1b.
Where in South Africa is it a problem?Mpumalanga and KwaZulu-Natal.
How does it spread?The seeds are dispersed by water and animals that eat the fruit. They may also be spread as a contaminant in agricultural produce or in mud sticking to animals, footwear, machinery and vehicles.
Why is it a problem?
It invades disturbed areas such as roadsides, fence lines, creek banks, grazed pastures and the edges of rainforests. It is a competitive weed in subtropical (summer rainfall) areas and is toxic to animals.
What does it look like?
Leaves: Leaves are borne on stalks 40-65mm long with 2-6 pairs of large leaflets 40-105mm long and 20-40mm wide. The leaflets are egg-shaped with the broad end at the base, or oval with pointed tips and entire margins. The surfaces are covered in greyish-white hairs. There is also a small, cone-shaped projection present near the base of each leaf stalk.
Flowers: The yellow to deep orange, irregular flowers are borne in small, unbranched clusters in the upper leaf forks or at the tips of the branches. These clusters usually contain 2-8 flowers. The flowers have five petals, 8-16mm long, which may become brown-veined as they mature.
Fruit/seeds: The slightly sickle-shaped brown pod is usually curved downwards, 10-18cm long and 4-6mm wide, and very slender, slightly flattened and covered in long, whitish hairs. They turn brown as they mature and are slightly indented between each of the seeds. The seeds are olive or brown, rounded in shape with a smooth surface.
Does the plant have any uses?
Planted as a shade or shelter plant in young coffee plantations, as a soil improver and as green manure. The leaves have medicinal properties.