Centrosema molle



Centrosema molle

Benth. 1837

pronounced: sec-TROH-sem-uh MOLL-ee

(Fabaceae — the pea family)

subfamily: Faboideae - the bean subfamily


common name: centro

Centrosema derives from the Greek κεντρον (kentron), any sharp point, and σημα (séma), a sign, omen; molle is from the Latin mollis, soft. Until recently, this species was known as Centrosema pubescens, but this name is now given to the species (including Belalto Centro) that was previously named Centrosema schiedeanum, and is not thought to be present in Australia.

Centrosema molle is a native of sub-humid and humid regions of the New World tropics, distributed between 22ºN and 22ºS. It is now naturalized in tropical Africa and Asia, from sea level to an altitude of 1,600 m. Here it is an agricultural escapee. It is grown as plantation ground cover, in mixtures for grazed pastures, as cut-and-carry forage, and as green manure. Although the flower colour is rather variable, most plants have a more lilac flower than the pale one pictured below, one of quite a few plants of this species appearing on Magnetic Island roadsides and in waste spaces at the end of the wet season.

This is a perennial twining and trailing legume that will climb nearby grasses and fences. Individual plants can spread up to 2 m from the strong taproot. The stems are up to 3 mm across, green, and soft at the tips, slightly hairy, becoming woody when old. The plant roots down vigorously at the nodes on moist soil.

The trifoliate leaf has elliptic, oblong-ovate or ovate-lanceolate leaflets 1–7 cm long, 5–45 mm wide, rounded at the base and mostly acuminate at the apex, slightly hairy, especially on the lower surface; the petiole is up to about 5.5 cm long, the stipules 2–4 mm long and persistent.

The inflorescence is an axillary raceme with 3–5 papilionaceous flowers, light to dark lilac in colour, sometimes white; each flower is subtended by 2 striate bracteoles; the calyx is campanulate with 5 unequal teeth; the standard orbicular, up to 3 cm in diameter, hairy on the outside, bright or pale lilac on either side of a median greenish yellow band with numerous dark violet stripes or blotches; the wings and keel are much smaller than the standard, and directed upwards.

The pod is linear, flattened, 4 – 17 cm long and 6 – 7 mm broad, straight to slightly bent and beaked, with prominent margins, dark brown when ripe and containing up to 20 seeds. The seeds are transversely oblong to squarish with rounded corners, 4 – 5 mm by 3 – 4 mm by 2 mm in size, brownish black, mostly with dark mottles.

The plants found on Magnetic Island are probably of the cultivar ‘Cardillo’, the only commercially available cultivar in Australia. It has a slightly different growth habit from common Centro, and is more widely adapted. It is not considered to have major weed potential, but it can be a minor nuisance in ungrazed areas because of its tolerance to shade and its climbing growth habit.

Photographs taken at Picnic Bay 2011
Page last updated 4th November 2018