Trifolium spp. African annual

Trifolium decorum Chiov.

Trifolium mattirolianum Chiov.

Trifolium quartinianum A. Rich.

Trifolium rueppellianum Fresen.

Trifolium steudneri Schweinf.

Trifolium tembense Fresen.

Trifolium usambarense Taub.

T. rueppellianum: Trifolium subrotundum Steud. & Hochst. ex A. Rich.

T. tembense: Trifolium umbellulatum A. Rich.

Family: Fabaceae (alt. Leguminosae) subfamily: Faboideae tribe: Trifolieae.

T. decorum:  Herbaceous annual to 50 cm tall, stems ascending, glabrous.  Leaflets ovate to suborbicular, 30‒45 × 18‒28 mm, narrowed towards base and with finely toothed margins, especially in the upper part.  Petioles up to 120 mm long on lower leaves, upper leaves short-stalked.  Stipules ovate-acuminate up to 10 mm. Inflorescences almost round 15‒25 mm diameter, 6‒15-flowered, long pedunculate of 20‒60 mm borne in the axils of leaves.  Calyx about 5 mm long, 15‒25 nerved; lobes triangular, 2‒3 mm long, sparsely pilose at the margins. Corolla purple, 10‒14 mm long, twice as long as calyx or more, standard slightly longer than the wings and keel.  Pods 6 mm long and 3-5 seeded.  Seeds oval, brown and usually 1.5 × 2 mm.

T. mattirolianum:  Herbaceous annual to 30 cm tall, erect or decumbent, branching all along deeply grooved stems, glabrous.  Leaflets obovate, up to 16 × 14 mm, usually truncate or emarginate at the apex;  margins finely spiny-toothed and veins prominent.  Petiole up to 50 mm long, in upper leaves much shorter.  Stipules with acuminate tips usually united to leaf stalks for about half of length, margins smooth or ragged.  Inflorescences 10‒20 mm diameter, globose, many-flowered.  Pedicels about 0.5 mm long; peduncle long, glabrous.  Calyx glabrous, 11-nerved, becoming somewhat inflated and constricted at the throat; lobes abruptly narrowed near the base, subulate, 2‒6 mm long.  Corolla purple or rarely white, 7‒10 mm long;  standard longer than the wings and keel.  Pods about 3 mm long, enclosed in calyx tube, 1‒2-seeded and not dehiscent.  Seeds oval, brown and usually up to 1.5 × 2 mm.

T. quartinianum:  Herbaceous annual to 60 cm tall, sub-glabrous, with stout, erect or spreading, grooved and branched stems. Leaflets narrowly oblong, approximately 52 × 16 mm with fine teeth. Petioles up to 40 mm long on lower leaves. Stipules 10‒20 mm long with narrowly triangular tips. Inflorescences about 20 mm in diameter and globose, long-pedunculate, bracts several-nerved forming an involucre, outer bracts ovate, lobed or toothed, up to 7 mm long. Calyx about 40-nerved, lobes 4‒7 mm long, ovate and overlapping at the base, drawn out into subulate points. Corolla purplish red, occasionally white, 11‒12 mm long.  Pods about 4 mm long and 4‒5 seeded. Seeds oval, brown and usually 1.5 × 1 mm.

T. rueppellianum: Herbaceous annual  to 50 cm tall, stems glabrous or pilose, erect or decumbent.  Leaflets oblong or obovate, approximately 24 × 18 mm, rounded to emarginate at the apex, glabrous or sparsely pilose, toothed margin.  Petiole up to 7 cm long, in upper leaves short or wholly united with stipules.  Stipules up to 15 mm long, united with petiole for two thirds of their length, with acuminate tips, entire.  Inflorescences globose, usually 15‒30-flowered, about 17 mm across. Pedicels up to 2 mm long. Peduncle long, pilose near the top, bracts minute. Calyx glabrous or pilose, usually 11-nerved; lobes abruptly narrowed near the base, subulate for most of their length, 2‒5 mm long and sometimes exceeding the corolla.  Corolla purple or rarely white, 5‒8 mm long. Pods 3‒4 mm long and usually 2‒3-seeded. Seeds oval, brown and usually 1.5 × 1 mm.  This is a very variable species and several distinct ecotypes have been identified.

T. steudneri: Herbaceous glabrous annual to 60 cm tall with many erect to spreading, grooved stems.  Leaflets narrowly elliptic, approximately 40 × 8 mm, margins finely toothed.  Petioles up to 50 mm long with upper leaves on shorter petioles.  Stipules up to 25 mm long with narrowly triangular tips.  Inflorescences globose, about 10‒20-flowered, up to 13‒20 mm across, short-pedunculate.  Bracts several-nerved forming an involucre, outer bracts abruptly and sharply pointed, up to 7 mm long, inner bracts oblong, 3 mm long.  Calyx about 40-nerved, glabrous or occasionally pilose; lobes triangular, 2‒3 mm long.  Corolla purplish, 7‒8 mm long, sometimes with filiform tips.  Pods 4 mm long and usually 2‒4-seeded.  Seeds oval, brown and usually 1.5 × 2 mm.

T. tembense: Herbaceous annual, stems numerous, erect or spreading, sometimes rooting at the nodes, glabrous or nearly so.  Leaflets elliptic or obovate, approximately 20 × 10 mm, narrowed at the base and with toothed margins.  Petioles up to 5 cm long, in upper leaves very short or wholly united with stipules.  Stipules about 15 mm long and with the free part abruptly contracted to a fine point.  Inflorescences usually globose, 3‒16-flowered, up to 23 mm across, long pedunculate.  Calyx 5‒7 mm long, sparsely pilose at margins, 11-nerved; lobes about 5 mm long, twice as long as tube and gradually narrowing from the 1.5 mm wide base, with broad scarious margins.  Corolla purple or rarely white; standard longer than wings and keel and about 9 mm long, abruptly narrowed above the middle into an oblong, truncate, down-curved tip.  Pods 5‒8 mm long, glabrous, 4‒6 seeded.  When ripe, pods dehisce along the top prominent margin for seed dispersal.  Seeds oval, brown and usually 1.5 × 1 mm.

T. usambarense: Annual or short-lived herbaceous perennial with stems erect or ascending, to 1 m long, branching throughout, glabrous below, sparsely pilose above, often rooting at the lower nodes.  Leaflets cuneate-oblanceolate, 6‒22 × 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 × 7‒13 mm.  Peduncle to 6 cm long, pilose above; bracts minute.  Calyx usually pilose, 10‒11-nerved; lobes subulate, about 3 mm long.  Corolla purple (rarely white) with broad elliptical standard, 4‒7 mm long.  Pods 2‒3 mm long and usually 2-seeded.  Seeds oval, brown and usually 1.5 × 1 mm.

T. quartinianum

English: Quartin’s clover

T. rueppellianum

English: Rueppell's clover

T. steudneri

English: Steudner's clover

T. tembense

English: Tembien clover

T. usambarense

English: Usmabara clover; German: Usambara-Klee; Chichewa, Malawi: therere

T. decorum, T. mattirolianum

Native: Africa:  Ethiopia

T. quartinianum

Native: Africa:  Eritrea; Ethiopia; Uganda

 T. rueppellianum

Native: Africa:  Cameroon; Democratic Republic of the Congo; Equatorial Guinea (Bioko); Ethiopia; Kenya; Rwanda; Sudan; Tanzania.

Cultivated: Widespread in tropical Africa.

 T. steudneri

Native: Africa:  Eritrea; Ethiopia; Kenya; Uganda  

T. tembense

Native:  Africa:  Democratic Republic of the Congo; Eritrea; Ethiopia; Kenya; Rwanda; Tanzania; Uganda

T. usambarense

Native: Africa: Burundi; Cameroon; Democratic Republic of the Congo; Ethiopia; Equatorial Guinea (Bioko); Kenya; Malawi; Nigeria; Rwanda; Tanzania; Uganda; Zambia

Forage

The East African annual Trifolium spp. are considered to make a valuable contribution in native pasture grazing systems, with potential for use as annual legumes for pasture improvement in high altitude areas.  They can be used for intercropping with wheat or barley in tropical highlands to improve quality of residues for livestock feed, and can also be used for hay and silage production.

Environment

Used for intercropping with wheat or barley in tropical highlands to improve soil nitrogen.

Other

These are all excellent species for bee keeping and honey production.

Soil requirements

These Trifolium spp. are well adapted to a wide range of soils from heavy clay vertisols and nitosols to loams and sandy loams, mostly from pH 4 to 8.  T. quartinianum grows particularly well on acid soils. T. tembense can tolerate low P.

Moisture

Although best adapted to good moisture conditions and tolerant of seasonal waterlogging, many of the annuals, particularly T. steudneri, are also quite drought tolerant by virtue of a deep root system.  Annual rainfall in natural range: T. decorum (1,000‒2,000 mm); T. mattirolianum (1,100‒2000 mm); T. quartinianum (800‒1,900 mm); T. rueppellianum (700‒2,000); T. steudneri (700‒2,000 mm); T. usambarense (1,200‒1,600 mm).  T. tembense is regarded as a good legume for seasonally waterlogged areas.

Temperature

This group of African clovers is found in the cool, largely frost-free tropical highlands.  Although well adapted to the highlands, ground temperatures below 7 °C during the growing season retard growth and an elevation of 2,600 metres above sea level is about the upper limit for good forage production in tropical areas.  Altitude range for the native area of the various species: T. decorum (1,800‒3,000 m asl); T. mattirolianum (1,300‒2,700 m asl); T. quartinianum (1,500‒2,600 m asl); T. rueppellianum (1,500‒3,650 m asl); T. steudneri (1,100‒2,800 m asl); T. tembense (1,400‒3,200 m asl); T. usambarense (1,600‒2,700 m asl); T. mattirolianum (1,300‒2,700 m asl).  T. decorum  is one of the best Trifolium species for use in higher altitudes during the rains when there is no frost.  T. steudneri can be grown at lower altitudes than any of the other Ethiopian indigenous clovers and is best suited to middle altitudes of around 1,800 m asl with moderate rainfall.

 Light

Competition for sunlight can lead to domination of stands by some of the clovers that express rapid regrowth or tall stature.

 Reproductive development

Time to maturity has been tested in the equatorial uplands with approximately 12-hour days. T. decorum flowers from 70 to 110 days after planting (dap), a couple of leafy later flowering genotypes appearing to have potential as fodder (see 'Promising accessions').  T. mattirolianum flowers from 94 to 140 dap, usually close to the end of the rains, seeds maturing into the dry season.  Unlike the morphologically similar T.ruepellianum, T. matirrolianum is allogamous.  T. quartinianum flowers from 65 to 100 dap, producing large flowers to attract bees for pollination.  T. rueppellianum flowers at the end of the rains, from 60 to 100 dap; autogamous and high seed producers. T. steudneri is fast maturing and flowers in August during the wet season (50‒90 dap).  T. tembense is early maturing and flowers near the end of the rains (65‒110 dap).  T. usambarense is very early flowering, 50‒90 dap.

Defoliation

The annual clovers tolerate moderate to high grazing pressure.  Grazing late in the season reduces seed heads leading to reduced regeneration in following years.  They respond well to defoliation and compete better with grasses when the pasture is cut to about 5‒10 cm.  T. tembense makes good quality hay, although leaf drop occurs when mature.

Fire

Fire is rarely an issue in areas where Trifolium spp. are found.

Guidelines for establishment and management of sown forages.

Establishment

While most are usually sown at 1‒2 kg/ha, T. tembense is sown at 5‒6 kg/ha.  Seeds are hard and require scarification before planting to ensure uniform germination.  Seedbeds should be well prepared to a fine, firm tilth.  Seeds are best sown just below the surface, lightly covered and rolled.  Seeds can also be sown directly into grass stubble, with no further seedbed preparation, and covered using a roller or by light disking.  Germination occurs in about 5‒7 days and young seedlings can be observed about 2 weeks after planting.  T. quartinianum is somewhat promiscuous in rhizobium requirements nodulating on several inoculum strains, unike the others that are usually highly specific.  In their native habitat they nodulate readily with native rhizobia and nitrogen fertilizer is not required.  T. decorum fixes the equivalent of 85‒112, T. quartinianum 80‒120, T. rueppellianum 80‒100 and T. steudneri 40‒65 kg/ha N.  Although this is low compared with the other African annual clovers, nitrogen fertilizer is still not required.

Fertilizer

Fertilizer (di-ammonium phosphate (DAP)) is generally recommended when grown on poor soils at a rate of 25‒30 kg/ha P with large dry matter yield increases seen in response to P application on poorer soils.  The application of 30 kg/ha P can lead to a significant increase in  root weight and the number of nodules in T. rueppellianum, T. steudneri and T. tembense.

 Compatibility (with other species)

Annual clovers combine well with other annual clovers and short-growing grasses.  When grown together with T. quartinianum, grasses were reported to accumulate more dry matter, crude protein and and have higher IVDMD than when the grass is grown as a monoculture.  They have been used successfully for intercropping with wheat and barley without significant reductions in grain and straw yields.  

Companion species

Grasses:  Cenchrus clandestinus, Cenchrus geniculatus, Cenchrus sphacelatus, Cynodon dactylon, Setaria sphacelata.

Legumes:  Lotus uliginosus, Neonotonia wightii, Trifolium decorum, T. quartinianum, T. repens, T. rueppellianum, T. semipilosum, T. steudneri, T. tembense, T. usambarense.

Pests and diseases

Under cool damp conditions seedlings are sensitive to damping-off disease, mainly caused by the soil-borne fungal pathogen Pythium spp., which results in rapid seedling death.  Plants are susceptible to red spider mites (Tetranychus urticae Acarina: Tetranychidae) when grown in the greenhouse or shade areas.  T. rueppellianum is susceptible to root-knot nematode, Meloidogyne incognita.

Ability to spread

Plants tend to 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.  Substantial seed reserves of T. quartinianum, T. rueppellianum, T. steudneri and T. tembense were revealed in the top 5 cm of soil after 4 years of fallow in Ethiopia.

Weed potential