Senna obtusifolia, Senna hirsuta and Senna tora
This is a vigorous shrub growing up to 2 metres high and 1 metre wide.
Leaves are divided into 3 pairs of opposite leaflets each about 4 centimetres long and 2 centimetres wide, rounded at Senna hirsutaare pointed at the tips.
Flowers are yellow, about 1 centimetre across with 5 petals, in pairs in axils of upper leaves. It flowers during autumn. The flowers of Senna hirsutaare are larger and are found in clusters of 2 to 8.
Seeds the pod is slender, sickle-shaped and is 10 to 15 centimetres long and slightly indented between seeds. Seeds are dark brown and flattened. The seed pods of Senna hirsutaare are rounded, hairy, slightly curved and occur in clusters.
Habitat it grows in disturbed areas such as roadsides, drainage channels and overgrazed pastures, along rivers and floodplains, fence lines and creek banks often in dense thickets. It prefers drained, fertile soils.
Weed characteristics aggressively invades and can completely dominate grass species, reducing pasture growth. It impacts on native ecosystems.
Dispersal seeds remain viable for 8 to 10 years. It spreads mainly through livestock.
This species is a Class 2 declared plant under Queensland legislation.
How to act
Foliar spray works well on this plant. Hand pulling some smaller plants can also be effective. Slash plants before seed matures, burn to stimulate seed bank, spray emerging seedlings with a broad-leaved selective herbicide. Foliar spraying will then control and reduce populations.
Refer to Weed Control Methods.
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