pronounced: sty-loh-SAN-theez SKAB-ruh
Stylosanthes is derived from the Greek στυλος (stylos), a pillar used as a support (i.e. a style), and ανθος (anthos), a flower; scabra is from the Latin scaber, rough.
This South American native is an erect to sub-erect shrubby perennial that can grow to 2 m tall, with a strong deep taproot that can reach down into the ground as far as 4 metres. Young stems vary from green to reddish in colour, depending on the strain. They usually have dense hairs and bristles, and are viscid, becoming woodier with age.
The leaves are trifoliate; the leaflets are hairy on both surfaces, elliptic to oblong-lanceolate, pale green to dark green and dark blue-green in colour; the terminal leaflet is 20 – 33 mm long and 4 – 12 mm wide. The stipules are obovate, bristly hairy, 15 – 25 mm long, including teeth.
The inflorescence is a broad, loosely formed and shortly elongate spike, occurring singly in the leaf axils.
The fruit is a 2-segmented pod, both segments usually being fertile. The upper, hooked segment is 4 – 5 mm long, including the 1 – 2 mm hook, and the hairy lower segment 2 – 3 mm long. The seeds are kidney-shaped, to 2 mm long, pale to light brown. They are spread through ingestion by grazing animals, and by water movement. Both hooked and hairy segments of the fruit can also adhere to animal fur or human clothing.
The plant was introduced to Australia as a pasture plant for the dry tropics. It is highly drought-resistant due to its deep taproot. It is generally oversown into native pastures, and, once it has become established, is a very strong competitor, able to persist with most companion species, including Cenchrus ciliaris (Buffel grass). Regrowth following grazing is normally from buds along the aerial stems, which, being woody, are rarely removed. When mown, strong and rapid regrowth occurs from crown buds at, or even slightly below, ground level. Normally, the plant is continuously but lightly grazed; but, under extensive conditions, animals tend to ignore it until fairly late in the season, when more palatable fodder is becoming scarcer.
There are various cultivars available, of which ‘Seca’ and ‘Fitzroy’ are the two now generally used in Australia.