Arachis glabrata Benth.

Synonym

• Arachis prostrata Benth. (1841)

Rhizoma peanut (USA), creeping forage peanut (Australia).

Native to Brazil, Argentina and Paraguay between 13° S and 28° S. Introduced to Australia, the United States, India, Thailand, Malaysia and Indonesia.

Herbaceous perennial with erect to decumbent unbranched stems with a deep, woody taproot and a dense mat of rhizomes. Leaves glabrous to sparsely pubescent, tetrafoliolate; leaflets ranging from linear-lanceolate to oblanceolate, obovate or cuneate up to 4 cm x 2 cm; apex acute to mucronate, base mostly obtuse; petiole grooved, up to 7.5 cm long, 1-2 mm diameter with pulvinus 10-15 mm above axil; stipules linear-lanceolate, falcate, up to 3 cm long, adnate to the petiole and membranous below the pulvinus; petiolule about 1 mm and rachis 10-15 mm long. Flowers sessile, axillary; hypanthium filiform, tubular, up to 10 cm long, pilose, containing the ovary at its base; standard more or less orbicular, 15-25 mm wide, yellow, soft orange to brilliant orange without red veins on back. Fruit set geocarpic, but usually scarce; fruit ovoid ca. 10 mm x 5-6 mm. Seeds ovoid, whitish.

Uses

A. glabrata is a high quality forage legume for intensively grazed pastures on infertile, acid soils. It has potential for soil conservation and as an ornamental. It is used for hay production in Florida, and is showing promise under coconuts in Indonesia

Best growth takes place in the warm rainy season but it can survive dry seasons of 4 months or more. During very dry conditions aerial growth may die off. Plants regrow vigorously with the onset of warm and humid weather.

Frosts, may cause top growth to die off, but plants recover from rhizomes.

Altitude range

A. glabrata is essentially a lowland species growing best at latitudes 30°N and S to near the equator.

It is best suited to areas receiving 1000-2000 mm per year, but it will persist in areas receiving 750 mm.

Slight.

Grows successfully on well-drained soils ranging from sands to clays. Prefers acid soils, but tolerates neutral to slightly alkaline soils. Develops excellent ground cover on poor soils.

Requires specific inoculant, which can be overcome by vegetative planting.

Rhizomatous habit ensures easy spread; dense swards extend at the margins at up to 2 m per year in the absence of competition, or 5-30 cm per year with grass competition.

A clean seed-bed is preferred, to minimize competition for the developing plants.

Due to lack of seed set it is usually planted vegetatively.

Despite often dense flowering, few seeds are formed.

Grows well in soils low in P, but some P fertilizer is advisable for soils extremely low in P. Liming is rarely necessary.

Combines well with aggressive creeping grasses such as Brachiaria decumbens, Paspalum notatum, Axonopus affinis, Digitaria eriantha and Cynodon dactylon.

A. glabrata is usually propagated from rhizomes. Best results are obtained by planting 30 cm² pieces of rhizome mat about 1.8 m apart. Alternatively, the rhizomes can be loosened, broadcast over the surface at the rate of about 3.5 m³ of rhizomes/ha and disked in to a depth of 3 cm in clay soils to 6.5 cm in coarse sands. Shoots will develop 2-3 weeks after planting; seedlings are usually quite large before they form rhizomes. Equipment for harvesting and planting rhizomes has been developed in Florida.Weeds should be controlled during establishment by manual weeding or through use of pre-and post-emergence herbicides such as trifluralin or vernolate, post-emergence applications of alachlor and dinoseb, and routine applications of bentazon or 2,4-DB for broadleaf weed control, and sethoxydim and fluazifopbutyl for grass control, as required. Mowing and early grazing reduces shading from taller weeds and promotes spread of A. glabrata.

Very tolerant to heavy grazing (Cook 1992).