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Fruits. Copyright CSIRO
Leaves, flowers and flower buds. Copyright CSIRO
10th leaf stage. Copyright CSIRO
Cotyledon stage, epigeal germination. Copyright CSIRO
Scale bar 10mm. Copyright CSIRO
Centrosema pubescens Benth.
Bentham, G. (1837) Commentationes de Leguminosarum Generibus: 55. Type: Ad Tlalpuxahua Mexicanorum. Keerle in herb Martius..
A slender vine not exceeding a stem diameter of 2 cm.
Stipules triangular, about 1-2 mm long, longitudinally veined, caducous. Middle leaflet larger than the lateral leaflets. Middle leaflet blade about 3.5-8.5 x 1.5-4 cm, lateral leaflet blades about 2-6.5 x 1.2-3 cm. Lateral leaflet stalks about 1-3 mm long, transversely wrinkled. Terminal leaflet 'stalk' about 6-15 mm long, pulvinus present. Leaflet blades clothed in pale or translucent hairs on both the upper and lower surfaces. Stipels subulate, usually apparent on the leaflets.
Flowers borne in a condensed umbel-like raceme, peduncles 7-8 cm long. Flowers about 3-3.5 cm diam., inverted. Calyx lobes variable, two short and similar in shape, two larger, similar, +/- triangular and one subulate about 6-7 mm long. All other petals enclosed by the standard at the flower bud stage. Petals: standard about 3 cm long, apex retuse, cream to green and pubescent on the outer surface, inner (adaxial) surface purple, marked with darker stripes and a central cream stripe, glabrous; keel about 22 mm long. Stamens 10, the filaments of nine stamens fused to form a tube open on one side. One stamen free. Free part of the filaments alternately long and short. Disk annular, surrounding the base of the ovary. Style or stigma ending in a broad strap-like tip, apex hairy. Ovules about 20.
Fruits flattened, about 12-16 x 0.5-0.6 cm, drawn out into a point at the apex, margins thickened. Seeds about 20 per fruit. Seeds ellipsoid or +/- patelliform, about 4-5 mm diam., funicle fawn-coloured, testa pale brown with black markings. Hilum comparatively large. Cotyledons much wider than the radicle which is about 1.5 mm long.
First leaves elliptic to cordate, apex +/- apiculate, base auriculate to cordate, midrib raised on the upper surface. Petiole with a pulvinus and a pair of stipels at the apex. Stipules about 2 mm long. Third leaf trifoliolate. At the tenth leaf stage: leaf trifoliolate with the middle leaflet larger than the lateral leaflets. Lateral leaflet blades about 1.8-5 x 1.8-2 cm, stalks about 0.2-0.3 cm long. Stalk of the middle leaflet longer than those on the lateral leaflets. Stipules triangular, about 3 mm long, venation longitudinal and parallel. Stipels filiform, about 2-3 mm long. Seedling twining.
Distribution and Ecology
An introduced species originally from South America. Naturalized in NT, CYP, NEQ and southwards almost to south-eastern Queensland. Altitudinal range from near sea level to 800 m. Usually grows on pastures but also in disturbed areas in monsoon forest and rain forest. Also naturalized in Asia and Malesia.
This species is the most important pasture legume in the wet tropics. Hacker (1990).