What Does It Look Like?
What is it?
Hairy Senna (Senna hirsuta) is a large upright herb or small shrub growing to 0.5–3 m tall. The stems, leaves and seed pods are all densely covered with long greyish-white hairs. Leaves are stalked and consist of three to six pairs of large leaflets up to 105 by 40 mm in size. These leaflets have pointed tips, and the leaf stalks bear a small finger-like gland.
The yellow to deep orange-yellow flowers have five petals 8–15 mm long and they are borne in small clusters in the leaf forks. These clusters usually contain 2–8 flowers and their petals may become conspicuously brown-veined as they mature.
The fruit is a very slender, flattened pod, 10-18 cm long, that is usually curved downwards. These pods are densely covered in long whitish hairs and turn brown as they mature (Navie 2004). For further information and assistance with identification of Hairy Senna contact the herbarium in your state or territory.
Growth form (weed type/habit)
Where it currently grows? Preferred habitat
Hairy Senna is a potential weed of disturbed sites, waste areas, roadsides, waterways, plantation crops, forest margins, open woodlands, pastures, grasslands and coastal environs in tropical and sub-tropical regions. In Asia, Hairy Senna grows on plains and hilly areas and spontaneously in waste locations, along roadsides, railway embankments, dry ditches and in secondary forest. It is found in gardens and fields as a weed, and prefers open locations (Navie 2004; ICRAF undated).
Are there similar species?
Hairy Senna is very similar to Sicklepod (Senna obtusifolia), Java Bean (S. tora), Coffee Senna (S. occidentalis), Smooth Senna (S. septemtrionalis) and the native Arsenic Bush (S. planitiicola). It is also relatively similar to Easter Cassia (S. pendula var. glabrata), Pepper-leaved Senna (S. barclayana), Candle Bush (S. alata), Popcorn Senna (S. didymobotrya) and Sesbania Pea (Sesbania cannabina var. cannabina). Hairy Senna can be distinguished from all these species by the long greyish-white hairs that cover the stems, leaves and pods. The leaflets of Hairy, Coffee, Smooth and Pepper-leaved Sennas, as well as Arsenic Bush, have pointed tips, while those of the remaining species are rounded. The pods of Hairy Senna are somewhat flattened, and straight to slightly down-curved. Those of the other species are all rounded or almost rounded in cross-section, apart from Candle Bush and Popcorn Senna which can be distinguished by their numerous (more than seven) pairs of leaflets (Navie 2004).