Conyza sumatrensis (PROSEA)
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Introduction |
Conyza sumatrensis (Retz.) E.H. Walker
- Protologue: Journ. Jap. Bot. 46: 72 (1971).
- Family: Compositae
- Chromosome number: 2n= unknown
Synonyms
Erigeron sumatrensis Retz. (1789), Erigeron linifolius auct. non Willd.
Vernacular names
- Fleabane (En)
- Indonesia: jalantir, monyenyen (Sundanese), sembung (Javanese)
- Malaysia: chapa, sawi bulan, tembak-tembak hutan
- Vietnam: cúc voi.
Origin and geographic distribution
C. sumatrensis originates from South America, but has at present a pantropical distribution. It has even spread as a weed to more temperate areas, e.g. in Europe.
Uses
In Java pounded C. sumatrensis root enters into a compound prescription to treat lumbago. A paste of ground leaves is applied as a poultice on the forehead to soothe headache. In Peninsular Malaysia leaves are used to treat rheumatism or lumbago. A root decoction may be taken as a post-partum protective medicine. In Africa leaf juice is applied in a poultice as febrifuge for small children, or simply rubbed on the body in adults. Leaf sap is used as a remedy for ophthalmia in the form of nose or eye drops. Nasal drops are also given in cases of vertigo and epilepsy. The leaves are made into cigarettes to treat tuberculosis and asthma. They may be used as a vegetable.
Properties
In a general screening experiment, the essential oil from C. sumatrensis leaves was markedly effective against Aspergillus niger even at low concentrations (1 μl/ml growth medium). Lachnophyllum lactone and osthol isolated from C. sumatrensis exhibited repellent activity against sea snails.
Botany
A short-lived perennial, erect herb up to 350 cm tall, strongly branched in upper part. Leaves alternate, simple, oblanceolate to linear-oblanceolate, 3-12 cm × 0.3-3 cm, gradually tapering at base, larger ones sparsely coarsely dentate-serrate in the upper part, smaller ones often entire, grey-hairy on both sides, sessile; stipules absent. Inflorescence a small cylindrical head 5-6 mm long, many together arranged in a long leafy panicle, many-flowered, shortly peduncled; involucral bracts 3-seriate, linear, 2-5 mm long, erect, later patent, in fruit reflexed. Flowers all tubular, c. 4 mm long; marginal flowers female, corolla with 2-lobed apex, pale yellow to purplish, shortly exserted from the involucre; disk flowers bisexual or male, with narrowly funnel-shaped corolla widening into 5 lobes, pale yellow; stamens 5, forming a tube, exserted; ovary inferior, 1-celled, style with 2 short, thick arms. Fruit a small, compressed, ellipsoid achene 1.5-2 mm long, with narrowed base and thickened margins, sparsely hairy; pappus hairs numerous, 1-2-seriate, 3-4 mm long, thin, toothed. Seedling with epigeal germination; hypocotyl c. 1 mm long; cotyledons subsessile, elliptical to ovate; epicotyl absent.
C. sumatrensis can be found flowering and fruiting throughout the year. It has no seed dormancy, and the fruits are wind dispersed.
Conyza comprises about 60 species, and occurs primarily in tropical and subtropical regions. Several species are widespread weeds, e.g. C. bonariensis (L.) Cronq. and C. canadensis (L.) Cronq.
Ecology
C. sumatrensis occurs gregariously in sunny or slightly shaded, dry or moist localities on a wide range of soils in regions with a weak or pronounced dry season. It can be found in grassland, roadsides, wasteland, fields, secondary forest, and rubber and tea plantations, from sea-level up to over 3000 m altitude.
Management In South-East Asia C. sumatrensis is considered a not too harmful weed. It is relatively easy to remove during the early stages of its development, but more difficult when the stem base has become woody.
Genetic resources
C. sumatrensis is a pantropical weed, well adapted to disturbance and is not threatened by genetic erosion.
Prospects
Little is known about the pharmacological properties of C. sumatrensis . Further research is needed to evaluate the potential of its traditional medicinal uses.
Literature
120, 121, 208, 334, 879.
Other selected sources
62, 112, 667.
Main genus page
Authors
J.L.C.H. van Valkenburg
