Trifolium usambarense  Taub.

Family: Fabaceae (alt. Leguminosae) subfamily: Faboideae tribe: Trifolieae. Also placed in: Papilionaceae.

Annual or short-lived perennial with stems erect or ascending, up to 1 m long branching throughout, glabrous below, sparsely pilose above, often rooting at the lower nodes.  Leaflets cuneate-oblanceolate, 6-22 x 3-7 mm, usually rounded at the apex and narrow at the base, glabrous or nearly so.  Petioles united with stipules for all their length;  stipules about 10 mm long with the free part triangular-acuminate.  Inflorescences globose or elongate ovoid borne both terminally and in the axils of leaves, many-flowered, 9-18 x 7-13 mm.  Peduncle up to 6 cm long, pilose above;  bracts minute.  Calyx usually pilose, 10-11-nerved;  lobes subulate, about 3 mm long.  Corolla purple or rarely white with broad elliptical standard , 4-7 mm long.  Pods are 2-3 mm long and usually 2-seeded.  Seeds oval, brown and usually 1.5 x 1 mm.

Native to:
Africa:   Burundi, Cameroon, Democratic Republic of Congo, Ethiopia, Kenya, Rwanda, Tanzania, Uganda.
Found in grasslands and riverine margins.

Other:
Widespread in tropical Africa.

Regarded as a good legume for grazing in native pastures with potential for use as an annual legume for pasture improvement in high altitude areas.  An excellent species for bee keeping and honey production.

The species is well adapted to a wide range of soil types from lighter acid sandy-loams to clays.  It can tolerate heavy clay vertisols and waterlogging .

Adapted to high rainfall areas.  Rainfall in its natural range varies from 1,200-1,600 mm/yr.

Adapted to the cool frost-free tropical highlands, the species is widespread in tropical Africa and occurs from 1,600-2,700 m altitude range.  It grows well in lower altitudes in grasslands where there is sufficient moisture.

No information available.

This is a very early flowering Trifolium species and flowers from 50-90 days after planting in areas close to the equator with approximately 12-hour days.

Clovers tolerate moderate to high grazing.  Grazing late in the season reduces seed heads leading to reduced regeneration in following years.

No information available.

Guidelines for the establishment and management of sown pastures.

Clovers are usually sown from seed at rates of 1-2 kg/ha.  Seeds are hard and require scarification before planting to ensure uniform germination.  Seeds are small and seedbeds should be well prepared to a fine, firm tilth.  Seeds are best sown just below the surface, lightly covered and rolled.  Germination occurs in about 5-7 days and young seedlings can be observed about 2 weeks after planting.  African Trifolium species are highly specialised in their rhizobium requirements.  In its native habitat it nodulates readily with native rhizobia and nitrogen fertiliser is not required.

Fertiliser (Di-ammonium phosphate DAP) is recommended when grown on poor soils at an optimum rate of 25-30 kg/ha P.

T. usambarense combines well with other annual clovers and short-growing grasses.

Grasses:  Pennisetum clandestinum , Eleusine jaegarii.
Legumes:  Trifolium burchellianum , Neonotonia wightii .

Under cool damp conditions, seedlings are sensitive to damping-off disease from the soil-borne fungi Pythium spp. resulting in rapid seedling death.  Roots susceptible to the nematode Meloidogyne incognita.  Plants are susceptible to red spider mites when grown in the greenhouse or shade areas.

Plants dry and die back after seed set, but hard seeds may be dispersed by water and small animals and remain in the soil for several years, allowing pastures to regrow annually.

This species is very palatable and intensively grazed, reducing seed set and dispersal.

Crude protein levels vary with genotype, age at harvest and environment and are about 20% when plants are harvested at late flowering stage.  Digestible dry matter is usually from 60-80% (weight/weight).

High palatability and nutritive value.

No information available.

Dry matter production responds well to increasing soil fertility and moisture.

Forage is beneficial for dairy and beef cattle and for horses but care should be taken not to use as a sole diet to avoid bloat.

2n = 16.  Plants are autogamous .

At least 1,000 mm rainfall is needed for good flowering and seed production.  Plants flower at the end of the rains and are pollinated by bees.  T. usambarense is a moderate seed producer because it produces only 2 seeds per pod , resulting in yields of around 400 kg/ha.  The percentage of hard seeds is often less than 50% but they store well.

No information available.

• Widely adapted to acid soils and low fertility in the tropical highlands.
• Well adapted to waterlogged heavy clay vertisols.
• Produces long stems that give good cover for soil erosion control.

• Requires high rainfall for good herbage and seed production.
• Cannot tolerate frost.

Dougall, H.W. (1962) The chemical composition of some species and varieties of Trifolium. East African Agricultural and Forestry Journal, 27, 142-144.

Gillet, J.M. and Taylor, N.L. (2001) The World of Clovers . Iowa State University Press.

Pritchard, A.J. and Mannetje, L. 't (1967) The breeding systems and some interspecific relations of a number of African Trifolium spp. Euphytica, 16, 324-329.

Wilson, G.P.M and Bowman, A.M. (1993) Trifolium species on the New South Wales north coast: 2. African species. Genetic Resources Communication, No. 19 .

Cultivars	Country/date released	Details
None released to date.

Promising accessions	Country	Details
None reported.