Commelina benghalensis L. - COMMELINACEAE - Monocotyledon

Common name : tropical spider-wort.

Botany Biology Phenology Ecology Distribution Cultural control Biological control Chemical control

Botany :

Description :

Annual or perennial, terrestrial, prostrate herb, 30—150 cm long, stolons present or absent, rooting at nodes. Roots white or brown, fibrous. Stem round, solid, hairy. Bracts (spathe) subtending the inflorescence, fused at the base, funnel-shaped, about 1.5cm long and wide shortly pedunculate. External surfaces of the spathe with white hairs. Stipules absent. Leaves evenly distributed on the stem, simple, not lobed or divided, alternate, stalked, lanceolate to elliptic or ovate, glabrous on both sides, margin entire, apex acute, base clasping or obtuse, parallel-veined. Leaf sheath present, rounded in cross section, hairy. Flowers bisexual, 3-merous, terminal or axillary, inflorescense few-flowered, petals 3, blue. Fruit a capsule, opening by 3 valves.

Seedling :

First leaves elliptic, 3 cm long and 2 cm wide, base attenuated into a petiole. Undulated margin pubescent lamina and parallel nerves.

Biology :

Dayflower is an annual (in temperature countries) or perennial herb (in tropics). It can propagates easily by layering (very resistant to dryness) but also by seeds. A plant can produce 1,600 seeds.

Phenology :

Flowering May to October, fruiting July to December.

Ecology :

The center of origin of dayflower is said to the Old World Tropics, although it occurs widely in southern Africa an in India eastwards to Australia, in tropics, subtropics and also in temperate areas. Present in upland rice in all countries of South and Southeast Asia. It occurs from sea level to 1,000 m, and grows best in under conditions of highs soil moisture and fertility, in sunny or lightly shaded places. It can persist in loamy, sandy, or rocky soils.

Distribution :

Tropical Africa, Asia and Pacific.

Cultural control :

It is particularly difficult to control by cultivation, partly because broken pieces of above and below ground stems readily take root. With hand weeding, it is necessary to uproot all the plant from the soil to ensure effectiveness.

Biological control :

Very few natural enemies have been reported to attack C. benghalensis and, of this, only two agromyzid leaf miners from the Americas appear promising (Amauromyza sp. and Liriomyza commelinae from Diptera family).

Chemical control :

Butachlor has been reported to provide good pre-emergence control of C. benghalensis, for post-emergence control, propanil at 2 kg ha-1 or 2-4-D with propanil can increase effectivness or Almix(Chlorimuron+metsulfuron) at 4 g/ha.
-Single treatment with contact herbicides destroys the foliage, but does not prevent regeneration. Application of 2,4-D (1.4-2.8 kg/ha), metribuzin (2.5-3 kg/ha), and glyphosate (1.8-2 kg/ha) resulted in almost complete kill and the treated plots were free of the weed for up to 4 months. Photosynthesis- inhibiting herbicides (e.g. paraquat and ametryne) were not effective.

Uses :
Although a weed in crop, dayflower is a useful forage plant in Indonesia and Philippines.
Leaves are used as human food, as medicine for infected wounds, for treating sterility and as mucilage for treating burns, sore eyes and sore throats.
In Philippines and India, the whole plants is considered demulcent, laxative and astringent, and applied for strangury. In Taiwan the aerial parts are used as a maturative poultice.

Remarks :
C. benghalensis differ from C. diffusa by the presence of red hairs at the margin of leaf sheath, by the bracts funnel-shaped, fused and by the sessile flowers.

References :
-Merlier H., Montegut J. 1982. Advantices Tropicales. Flore aux stades plantule et adulte de 123 especes africaines ou pantropicales. Orstom, Cirad-Gerdat, Ensh. Montpellier, France.
-Holm L. G.,Plucknett D. L., Pancho J. V., Herberger J. P. 1991. The world's worst weeds Distribution and biology. East-West Center by the University Press. Hawaii.
-Waterhouse D. F. 1994. Biological control of weeds: Southeast Asian prospects. ACIAR Monograph No 26, 302 pp.

Top of the page