Desmodium heterocarpon (PROSEA)
Desmodium heterocarpon (L.) DC.
- Protologue: Prodr. 2: 337 (1825) ( heterocarpum ).
- Family: Leguminosae
- Chromosome number: 2n= 22
Hedysarum heterocarpon L. (1753).
- Carpon desmodium (En)
- Indonesia: buntut meyong sisir (Sundanese), kaci (Javanese), akar entimor (Belitung)
- Malaysia: rumput kerbau derapah, kacang kayu betina
- Philippines: mangkit-parang (Tagalog), mani-mani (Visaya), huyo-huyop (Ifugao)
- Cambodia: baay dâm'nnaëp
- Vietnam: tra[n]g qu'a di qu'a.
Origin and geographic distribution
Carpon desmodium is distributed naturally from India and Sri Lanka through Burma, Thailand, Indo-China, Malesia, China, Taiwan, Ryukyu, Japan, to the Pacific Islands and Australia.
Although native to South-East Asia, carpon desmodium is grazed as a wild plant, but is not sown in the region. Cultivar "Florida" has been sown to a limited extent in Florida (United States) where it is used for grazing in mixtures with perennial grasses.
Carpon desmodium is lower in quality than many other forage legumes. A study done in the United States found that foliage contained 1.5-3.2% nitrogen. Tannin percentages of 2.1-3.1% have been measured. There are 700-800 seeds/g.
A perennial herb or low shrub with ascending or creeping stems 0.5-3.0 m long from a woody rootstock. Stems mostly much-branched at the base, and when young variously hairy, from almost glabrous to densely covered with more or less appressed hairs. Leaves with 3 leaflets, or often with 1 leaflet on seedlings or at the base of older stems; leaflets variable in texture, shape and size, mostly papery; the terminal one elliptical, ovate or obovate, (1.5-)2-6(-9) cm × (1-)1.5-3(-4) cm, indented or more or less pointed at the tip, sparsely covered with appressed hairs on the upper surface, the lower surface more densely covered with appressed silvery hairs and with prominent nerves; the lateral ones with the same proportions but up to 4 cm long. Inflorescence a dense axillary or terminal raceme; flowers pink, mauve, purple, violet or white, 4-7 mm long, mostly in pairs, each on a 3-5 mm long pedicel within the axil of a 5-8 mm long pointed bract. Pod 10-28 mm × 2-3 mm, erect to ascending, straight along the upper margin, undulate along the lower margin, the isthmus between the 4-8 articles 2/3-4/5 as wide as the pod which splits along the lower margin when ripe; articles quadrate, 2.5-3 mm long, glabrous or hairy. Seed broadly elliptical, ca. 1.5 mm × 2 mm.
Growth and development
Seedling growth of carpon desmodium is slow. Once established, it is a very long-lived legume which can persist for over 10 years regardless of grazing management. It requires a moderate soil P status for maximum growth. In Florida, 65% of the growth is during the summer and early autumn growing seasons. Under heavy grazing it develops a prostrate growth habit. It is self- or cross-pollinating; it selfs when flowers are tripped.
Other botanical information
D. heterocarpon is very polymorphic and has been variously delimited. In the last revision and emendation of Desmodium Desv. for Asiatic species, Ohashi defined this species in its widest sense and characterized it as having 1-3-foliolate glabrous leaves, elliptical, ovate or obovate terminal leaflets, inflorescences 3-13 cm long and erect or ascending pods with 4-8 transverse-oblong or tranverse-obovate articles shorter than 4.5 mm long and less than twice as long as broad. He subdivided the species as follows:
- ssp. angustifolium Ohashi: synonym: D. reticulatum Champ. ex Benth.; terminal leaflets narrowly ovate, acute or obtuse at apex, 3-6.5 times longer than broad; inflorescence 10-30 cm long, not branched; Burma, Thailand, Indo-China and China; with 2 formae.
- ssp. ovalifolium (Prain) Ohashi: see separate treatment.
- ssp. heterocarpon : terminal leaflets obovate, elliptical or oblong, sparsely to subdensely hairy above; inflorescence elongated; flowers 3-4 mm long, pedicels 4-7 mm long; pods sparsely to densely pubescent with white hooked and straight hairs up to 1.5 mm long; with 4 varieties.
Carpon desmodium is adapted to a fairly high rainfall of over 1200 mm a year, can withstand short periods of drought but does not tolerate prolonged flooding. It is tolerant of repeated light frosts, and in the tropics it grows up to 2500 m altitude. It prefers better-drained soils of light texture. It tolerates soil pH values of 4.3-5.0 with high Al saturation.
Establishment is by seed, sown at a rate of 3-10 kg/ha. A clean, firm seed-bed is desirable. It nodulates with native cowpea rhizobium. On neutral and alkaline soils, it may become micro-nutrient deficient.
Carpon desmodium is free of major fungal diseases, but is sensitive to various leaf-spots ( Cercospora sp., Pestalotiopsis versicolor). Anthracnose (Colletotrichum gloeosporioides, C. truncatum ) occurs in the south-eastern United States and South America but usually causes only slight to moderate damage. Powdery mildew (Oidium sp.) and wilt (Sclerotium rolfsii) have also been recorded. Root-knot nematodes (Meloidogyne arenaria, M. incognita, M. javanica) have been described as the worst pests of "Florida" in the south-eastern United States, but their significance in South-East Asia has not been documented. Little leaf, caused by mycoplasma-like organisms, has caused slight to severe symptoms in Central and South America. Web-worms and other insects, including bean leaf roller (Urbanus proteus) sometimes attack foliage and pods in rank stands. They may be controlled by grazing and then de-stocking for a period before harvesting the seed crop.
It is harvested by grazing, and in Florida (United States), it is reported to be very tolerant of heavy grazing.
Genetic resources and breeding
The wide diversity in the species could indicate potential for genetic improvement. Studies in Florida, largely based on accessions from Thailand, have suggested that some accessions are resistant to root-knot nematodes. Germplasm collections are maintained at ATFGRC (CSIRO, Australia), CIAT (Colombia) and USDA (Fort Pierce, Florida, United States). Breeding work is being carried out in Florida.
There has been little interest in this species outside of the south-eastern United States since its initial release as a pasture legume in 1979, and it is not anticipated that future plantings will be widespread.
- Bogdan, A.V., 1977. Tropical pasture and fodder plants. Longman, London. p. 343.
- Imrie, B.C., Jones, R.M. & Kerridge, P.C., 1983. Desmodium. In: Burt, R.L., Rotar, P.P., Walker, J.L. & Silvey, M.W. (Editors): The role of Centrosema, Desmodium and Stylosanthes in improving tropical pastures. Westview Press, Boulder, Colorado, United States. pp. 97-140.
- Knaap-van Meeuwen, M.S., 1962. Preliminary revisions of some genera of Malaysian Papilionaceae 5. A census of the genus Desmodium. Reinwardtia 6: 93-96, 251.
- Kretschmer, A.E., Bullock, R.C. & Wilson, C.L., 1990. Evaluation of a collection of Desmodium heterocarpon (L.) DC. from southeast Asia. Proceedings soil and crop science society of Florida 49. pp. 94-99.
- Lenné, J.M. & Stanton, J.M., 1990. Diseases of Desmodium species. Tropical Grasslands 24: 1-14.
- Ohashi, H., 1973. The Asiatic species of Desmodium and its allied genera (Leguminosae). Ginkgoana 1: 210-216.
- Ohashi, H. 1991. Taxonomic studies in Desmodium heterocarpon (L.) DC. (Leguminosae). Journal of Japanese Botany 66: 14-25.
- Skerman, P.J., Cameron, D.G. & Riveros, F., 1988. Tropical forage legumes. FAO, Rome. pp. 268-270.
J.B. Hacker & A.E. Kretschmer, Jr.