Macroptilium gracile (Poepp. & Benth.) Urb.
Macroptilium longipedunculatum (Mart. ex Benth.) Urb.
Phaseolus campestris Mart. ex Benth.
Phaseolus gracilis Poepp. ex Benth.
Phaseolus longipedunculatus Mart. ex Benth.
Family: Fabaceae (alt. Leguminosae) subfamily: Faboideae tribe: Phaseoleae subtribe: Phaseolinae. Also placed in: Papilionaceae.
Macroptilium gracile is a variable species. It is a short lived perennial herb to 60 cm high with trailing stems; vegetative parts shortly pilose; hairs of the stem retrorse. Leaves are trifoliate. Lateral leaflets are ovate with asymmetric bases, 20-44 mm long, 10-31 mm wide. The terminal leaflets are broadly lanceolate to deltoid, 25-48 mm long, 13-30 mm wide. Flowers are approximately 24 mm long and are grey-orange in colour. The flowers are held above the foliage in an inflorescence on a peduncle 18-33 cm long. Pods are small and linear, 35-70 mm long containing 10-18 seeds. Seeds are small, mottled light and dark grey, flattened ovoid in shape, approximately 300,000 per kg.
'Maldonado' is similar in appearance to siratro (Macroptilium atropurpureum ). The differences are that siratro has larger, deep purple coloured flowers, larger pods and seeds and lateral leaflets, which are lobed.
M. gracile is a native of tropical South and Central America. It is generally found at low altitude (2-250 m) in areas with annual rainfall between 960 and 1,300 mm.
M. gracile was evaluated in the Northern Territory of Australia as a component of grazed mixed pastures. It is well accepted by stock. It behaves as a biennial. On average 40% of plants will survive from one wet season to the next.