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Stylosanthes humilis Kunth 1823
pronounced: sty-loh-SAN-theez HEW-mih-liss
(Fabaceae – the pea family)
subfamily: Faboideae – the bean subfamily
common name: Townsville Lucerne, Townsville Stylo
Stylosanthes is derived from the Greek στυλος (stylos), a pillar used as a support (i.e. a style), and ανθος (anthos), a flower; humilis is Latin for ‘low, lowly, small’.
This is a prostrate to erect herbaceous annual 5–50 (sometimes 70) cm tall, usually with short white hairs along one side of the stem and often scattered short bristles on stem and nodes. Prostrate stems in contact with moist soil may develop adventitious roots away from the tap root. The leaves are trifoliate, the leaflets lanceolate or elliptic, acute, the terminal leaflet to 15 mm long and 3.5 mm wide, with prominent veins. The tiny flower (2–3 mm in diameter) is a typical pea flower, and yellow in colour. The flowers are not long-lasting: they are usually withered by early afternoon. The fruits are hooked, to aid their distribution by adhering to livestock. Seed is also spread by being ingested and passing through livestock, and by water movement..
Townsville Lucerne is not, despite its common names, a local. It is native to Costa Rica, southern Mexico, Nicaragua, Panama, Cuba, Columbia and Venezuela. It also occurs in northern and central Brazil, but it is not certain whether it is a native there, or naturalized. In Australia, it was introduced to the seasonably dry tropics in the 1920s as a cattle fodder; it spread rapidly and soon became naturalized, resulting in dense populations throughout tropical and sub-tropical regions; but it was virtually wiped out by the inadvertent introduction of anthracnose disease in 1973. This is a disease of warm humid areas, and infects a large variety of plants, trees as well as grasses. It is caused by particular fungi producing spores on the affected plant in tiny sunken fruiting bodies. These appear on leaves, stems, flowers or fruits as sunken spots, and these spots often enlarge and kill the plant tissues.
Since then it is no longer used as a commercial legume, but has been replaced mainly by naturalized Verano Stylo. There are residual stands of Townsville lucerne; but, in those wetter years when it becomes abundant, it usually gets wiped out by the disease. On Magnetic Island it has survived and flourished, growing prolifically in many roadside verges. There is a particularly lush stand in Picnic Bay, by the side of Granite Street between Picnic Street and the mall.
As a fodder crop, it was mainly used in mixed pastures. It grows well with other species provided that they are not tall. In its young stages, it is relatively less palatable than its associated grasses, but, as the pasture matures, cattle eat it more readily. Cattle raised on it, and familiar with it, will graze it readily even when it is young. It is free-seeding, and self-regenerating in permanent pastures.
It needs as much sunlight as possible to flourish. Its generally prostrate habits did not make it very suitable for cutting and making into hay or silage; but, when grown by itself, it could, if the growth were lush enough (usually because of the use of potash fertilizers), be made into hay, with the resulting product of quite good quality.
Photographs taken at Picnic Bay 2010
Page last updated 20th February 2017