Stylosanthes fruticosa (Retz.) Alston

Leguminosae

Synonyms

• Stylosanthes flavicans Baker
• Stylosanthes mucronata Wild.
• Stylosanthes bojeri Vogel
• Arachis fruticosa Retz.

African stylo.

Copiously branching woody herb, ascending shrub or undershrub, reaching 50 cm in height. Branches densely clothed with short yellowish pubescence. Leaflets oblanceolate, narrowed to both ends, long mucronate at the apex, 9 to 18 mm long, prominently nerved, both surfaces nearly glabrous. Flowers in dense oblong terminal heads. Pod with two articulations, about 6 mm long, both faces and remains of style densely silky (Andrews, 1952). Beaks 1.5 to 3 mm long, and the plant has evenly pubescent stems. (S. fruticosa has the beak of the loment 3.5 to 4 mm long and unilaterally pubescent stems; Mohlenbrock, 1963). It is a perennial which may behave as an annual in the subtropics.

Amenable to stable mixtures with perennial grasses such as Andropogon gayanus, Heteropogon contortus and Hyparrhenia sp.pl. In areas protected from grazing and intermittently mown, it forms a dense sward (e.g. Dodoma airstrip).

T. Mannetje (1965) found the plant to be day-neutral in its flowering response, though there was a tendency to flower more rapidly in the shorter day. Greater dry-matter production occurred under a 14-hour day length. However, the plant is little sensitive to day length within the range of 10-14 hours..It flowered in 52-60 days at a temperature range of 30/25°C for a 10 hours photoperiod, and in 68 days under a 14-hour photoperiod. Temperatures of 35/30°C prohibited flowering. In southern Queensland, Australia (lat. 27°30'S), it has seeded well ahead of frosts, and although some plants have been killed, others survive frosts of 3°C.

It is very drought tolerant and is adapted to rainfall from as low as 284 mm (occurring over a four-month rainy season, from June to September, with the following eight months completely dry, in the Kordofan Province of the Sudan) to 1000 mm on the coast at Dar-es-Salaam, Tanzania. It was successfully rainfed cultivated at Niono, Mali in the late 1970's under a MAR of 500 mm.

Commonly grows on sandy soils derived from granite, sandstone or coral, of low phosphorus status. Preliminary tests show it to be promising on sandy soils in northern Queensland and on red latosols in south Queensland, and to respond to phosphorus.

Native to the South Sahelian and North Sudanian ecozones from Senegal to Rep. of Sudan (Kordofan) and to East and South Africa. Found in the Sudan, Nigeria, Kenya, Uganda, Tanzania, Zambia, Mozambique, Zimbabwe and South Africa. Occurs from sea level to 1800 m.

This species seems to nodulate freely with local Rhizobia and does not seem to require inoculation in Africa. Norris (personal communication) has isolated a strain CB2618 from nodules brought from the Sudan.

Seed falls on ripening and germinates immediately under the mother plant if moisture and temperature are favourable. Seed kept in storage for 18 months had 90 percent hard seed in the pod. When dehulled and scarified, 60 percent of the seed germinated within ten days at 26.5°C. The percentage of hard seeds is high, around 80%, but after scarifying the germination rate raises to 60%.

Stylosanthes fruticosa is much sought after by all kinds of livestock and is grazed heavily by stock in the Sudan and Tanzania (Skerman, 1970). This stylo is suitable for the rehabilitation of fallow land.

Dry-matter production from small plots in Queensland was 6000 kg/ha from rows sown 1.5 m apart. The dry material consisted of 38% stem, 19% leaf, and 42% inflorescence, of which one-third was seed (i.e. 14% of the plant weight was seed). There were up to 28 seeds per inflorescence. Fodder production under South Sahelian and North Sudanian conditions may be expected to reach 3,000-6,000 kg DM / ha / yr.

All accessions in Queensland have proved extremely susceptible to anthracnose (Colletotrichum gloeosporioides).

Andrews 1952 ; Baumer 1975 ; Berhaut 1976 ; Gillett et al. 1971 ; Skerman et al. 1991.