- Protologue: Sp. pl. ed. 4, vol. 3(3): 1742 (1803).
- Family: Compositae
- Chromosome number: 2n= 36 (M. cordata); 36, 38, 72 (M. micrantha)
Major species and synonyms
- Mikania cordata (Burm.f.) B.L. Robinson, Contrib. Gray herb. 104: 65 (1934), synonyms: Eupatorium cordatum Burm.f. (1768), Mikania volubilis (Vahl) Willd. (1803).
- Mikania micrantha Kunth, Nov. gen. sp. pl. vol. 4: 105 (1820), synonyms: M. orinocenis Kunth (1820), M. subcrenata Hooker & Arnott (1836), M. umbellifera Gardner (1845).
General: mikania (En).
M. cordata :
- Mile-a-minute (En)
- Indonesia: brojo lego (Javanese), blukar (Sumatra), hila hitu lama (Ambon)
- Malaysia: akar lupang, ceroma, selaput tunggul
- Philippines: bikas (Bagobo), detidid (Igorot), uoko (Bontok)
- Thailand: khikaiyan.
M. micrantha :
- Bitter vine (En).
- Liane-serpent (Fr).
Origin and geographic distribution
Most species of Mikania are native to the Americas; the most widely distributed species M. cordata , however, is native to and widespread in South-East Asia including Hainan and Taiwan. M. micrantha is native to Central and South America; it was first observed in Fiji in 1907, in Java in 1951 and is now found in India, Sri Lanka, Malaysia, Indonesia, the Philippines, New Guinea and several Pacific Islands.
Although often considered a nasty weed, Mikania is sometimes tolerated as a spontaneous soil cover in plantation crops e.g. rubber and oil palm, where its growth is limited by shade or where it can be controlled by herbicides. In plantation crops that transmit more light, and to a lesser extent in annual crops, it is considered one of the most noxious weeds. It is especially troublesome in young plantations, where it can quickly overgrow the main crop.
Leaves of M. cordata constitute a highly palatable forage, especially to sheep. They are also used as a poultice for swellings (Taiwan), itches (Malaysia) and wounds (Indonesia).
The dry matter digestibility of M. cordata is about 50% and N concentrations range from 2.6-3.4%, Ca concentrations from 1.5-1.9% and P concentrations from 0.6-0.9%. It has high concentrations of Cu, about 18 mg/kg. It has been reported from Malaysia that Mikania cordata contains phenolic or flavonoid substances that inhibit the growth of other plants e.g. rubber, tomato and tropical kudzu (Pueraria phaseoloides (Roxb.) Benth.), and depress nitrification in soils.
- Perennial, trailing or climbing herbs.
- Stems branched, terete or angular.
- Leaves opposite, usually petiolate, simple and entire.
- Inflorescence composed of corymbosely or cymosely clustered, peduncled heads; head 4-flowered, homogamous; involucral scales 4, oblong, narrow, subequal.
- Corolla campanulate, 5-fid, tube narrow; receptacle small, naked; anthers obtuse at base, apex with appendages; style branches 2, slender, long exserting the corolla, pubescent, subobtuse at apex.
- Fruit an oblongoid, 5-angular achene, usually glabrous; pappus bristles numerous, uni-seriate, equal, scabrid or barbellate.
- Scandent herb, often forming a dense tangled mass.
- Stem subterete or irregularly angular, ribbed, up to 6 m × 2-3 mm, internodes 8-20 cm long, nodes thickened, sometimes with short hairs.
- Leaf blade triangular-ovate, 2.5-10 cm × 2.5-7 cm, base cordate or shortly contracted, margin crenate-dentate, sinuate or entire, apex acutely acuminate, subglabrous, dotted with glands beneath; petiole 1-4 cm long.
- Inflorescence composed of peduncled heads, combined into small dense corymbs, at the top of short lateral branches and in the axils of leaves; peduncle of corymbs very variable in length; peduncle of heads up to 6 mm long; head 6.5-7.5 mm × 1.5-2 mm; involucral bracts elliptical-oblong, 6 mm long.
- Corolla 3.5-4 mm long, yellowish-white; style branches 2.5 mm long, white.
- Achene 2-3 mm long, glandular, black-brown; pappus of 40-45 bristles, 3-4 mm long, white to reddish.
- Creeping or twining herb.
- Stem terete to ribbed, pubescent to glabrous; internodes 5-20 cm long.
- Leaf blade ovate, 2-13 cm × 3-10 cm, base cordate, margin undulate-dentate to subentire, apex acuminate, glabrous; petiole up to 8 cm long.
- Inflorescence an axillary or terminal panicle of corymbs; peduncle about 6 mm long; flower head 4-6 mm long; involucral bracts ovate-oblong 3-4 mm long, glabrous, apex acute.
- Corolla 2.5-3 mm long, white to greenish.
- Achene 2 mm long, black, with very small glands between the ribs; pappus of 33-36 bristles, 2-3 mm long, white.
Growth and development
Mikania spreads by seed or by rooting at nodes touching the soil. Even small pieces of stem, spread by people or animals, may grow into new plants. Flowering occurs throughout the year. Seeds are produced in large numbers and the pappus enables effective wind dispersal over long distances. With its rampant growth it can rapidly smother young tree crops and other plants, hence the common name of M. cordata : "mile-a-minute". It can rapidly form a tangled mass to a depth of 0.6-1 m. If undisturbed, it often spreads in massive circular patterns.
Other botanical information
Mikania comprises about 400 species, many of which are quite variable and difficult to identify. The 2 species treated here have long been considered as one species: M. scandens (L.) Willd. M. scandens, however, only occurs in the Americas. References to M. scandens from Asia usually refer to M. cordata. Distinctive characters of the 2 species are:
- M. cordata: heads 6.5-7.5 mm long; involucral bracts elliptical-oblong, 6 mm long; corolla yellow-white; achene 2-3 mm long.
- M. micrantha: heads 4-6 mm long; involucral bracts ovate-oblong, 3-4 mm long, shortly acute at apex; corolla white; achene up to 2 mm long.
M. cordata is adapted to hot, humid tropical environments with 1500 mm or more annual rainfall and plenty of sunlight, at altitudes ranging from sea level to 1600 m. Hence it is commonly found in young secondary jungle, forest clearings, abandoned ground, secondary regrowth areas, ravines, mountain slopes, roadsides, water courses, fallow land, low-lying areas along streams and rivers and open plantations. However, it can also persist with reduced vigour in plantations. It may even be found under closed canopies of 4-5-year-old rubber and oil palm, but it is then markedly etiolated and weakened. It is rarely found in plantations 5-15 years old.
M. micrantha is usually found in damp clearings in lowland forest, but occurs up to 3000 m altitude. In Indonesia, it is only found below 700 m altitude. It grows along streams and roadsides, on disturbed sites as well as in forests. In Latin America it is only rarely a weed, but in parts of Asia it is considered the most aggressive species.
Mikania can be a devastating weed in crops of tea, coconut, cocoa, rubber, oil palm, coffee, banana and sugar cane, and can smother leguminous cover crops. Spraying with herbicides can reduce its vigour and spread. Mechanical weeding may contribute to the distribution of Mikania by spreading pieces of stem. As a cover crop, Mikania quickly covers the soil, but produces only small amounts of organic matter or leaf litter compared with leguminous or grass covers. Yields of associated rubber and oil palm are often lower than with a bush or legume cover. This is attributed not only to competition for nutrients and water, but also to allelopathic compounds diffusing from the roots. It has been reported as being susceptible to parasitic growth of dodder, Cuscuta chinensis Lamk in Sri Lanka and C. australis R. Br. in Fiji and Malaysia. M. cordata is palatable to livestock, particularly to sheep. Where present, it is the first species to be eliminated when sheep graze pastures. It should not be the main component of forage for sheep. Instances of abortion, death of newborn lambs and of older sheep have been recorded in rubber plantations where it comprised more than 50% of the diet. There is evidence that these problems relate to the high Cu concentrations. In Africa, M. cordata is reported to be less palatable to cattle and intensive grazing may lead to disappearance of grasses in mixed swards. There is very little information about the productivity of Mikania. Dry matter yields of 4 t/ha have been found in Mauritius.
Genetic resources and breeding
It is unlikely that any germplasm collections or breeding programmes of Mikania exist.
M. cordata and M. micrantha are aggressive herbs that are primarily noxious weeds. They should only be used as a cover crop if a legume cover can not be economically maintained. M. cordata and M. micrantha are highly acceptable, aggressive forages, but further study should be given to their agronomy and to feeding systems using these species, so that grazing may contribute to the biological control of these serious weeds.
- Barnes, D.E. & Chandapallai, M.M., 1972. Common weeds of Malaysia and their control. Longman Malaysia Sendirian Berhad, Kuala Lumpur, Malaysia. p. 93.
- Broughton, W.J., 1977. Effect of various covers on soil fertility under Hevea brasiliensis Muell. Arg. and on growth of the tree. Agro-Ecosystems 3: 147-170.
- Chen, C.P. & Chee, Y.K., 1992. Mikania cordata (Burm.f.) B.L. Robinson. In: 't Mannetje, L. & Jones, R.M. (Editors): Forages. Plant Resources of South-East Asia No 4. Pudoc Scientific Publishers, Wageningen, the Netherlands. pp. 166-167.
- Devendra, C., 1979. Malaysian feedingstuffs. Malaysian Agricultural Research and Development Institute (MARDI), Kuala Lumpur, Malaysia. p. 29.
- Holm, L.G., Plucknett, D.L., Pancho, J.V. & Herberger, J.P., 1977. The world's worst weeds: distribution and biology. East-West Center, University of Hawaii Press, Honolulu, Hawaii, United States. pp. 320-327.
- Holmes, W.C., 1982. Revision of the Old World Mikania (Compositae). Botanische Jahrbücher 103: 211-246.
- Koster, J.T., 1935. The Compositae of the Malay Archipelago. 11. Mikania. Blumea 1: 503-510.
- Mangoensoekardjo, S. & Soewadji, R.M., 1977. Pengaruh penutup terhadap tanaman karet. 3. Ditinjau dari segi hasil [The influence of ground covers on rubber. 3. Effect on yield]. Bulletin Balai Penelitian Perkebunan Medan (Indonesia) 8(4): 117-124.
- Perry, L.M., 1980. Medicinal plants of east and southeast Asia: attributed properties and uses. MIT Press, Cambridge, Massachusetts, United States. p. 103.
- Wong, R., 1964. Evidence for the presence of growth inhibitory substances in Mikania cordata (Burm.f.) B.L. Robinson. Journal of Rubber Research Institute of Malaya 18: 231-242.
I.B. Ipor & H. Sutarno