Synonymes : Commelina cavaleriei H. Lév.
Common name : Dayflower, tropical spiderwort
Common name in Bengali : Dholpata, kanaibashi, kanai bashi, kanchira
Common name in Hindi : Kankaua
Bangla English Hindi Urdu
Diagnostic characters
Biology
Ecology and distribution
Nuisance
Weed control
Botany
Uses/Remark
References
Dayflower is a fleshy, ramified creeping, perennial (tropical and subtropical) or annual (temperate) herb, with high ability to root at the nodes. The plant is first creeping and later ascending to 40 to 50cm tall. The leaves are alternate and hairy with parallels nerves; the flowers are blue or lilac.
Dayflower is an annual (in temperate countries) or perennial herb (in tropics). It can propagates easily by layering (very resistant to dryness) but also by seeds. A plant can produce 1600 seeds.
The center of origin of dayflower is said to be 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 1000 m, and grows best in under conditions of high soil moisture and fertility, in sunny or lightly shaded places. It can persist in loamy, sandy, or rocky soils.
Dayflower is a weed in crop, grasslands, roadsides, and waste places. In rice and other lowland crops it can grow in the water and form enormous root-bundles. In pastures, it can become dominant.
It is a problem in many countries of southern Africa, as well as in India, Sri Lanka, Bangladesh and Southeast Asia. In Bangladesh can reduce rice yield by 50%.
- Cultural
It is a 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
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
Butachlor has been reported to provide good pre-emergence control of C. benghalensis, for post-emergence control, propanil at 2 kg ha-1 at 10 days after emergence or 2_4-D at 500 g/ha at 20-30 days is effective. Mixing thiobencarb at 1-3 kg ha-1 or 2_4-D with propanil can increase effectiveness or Almix (chlorimuron+metsulfuron) at 4 g/ha.
Habit
Creeeping annual or perennial herb, stems creeping-ascending to 50cm tall; branched, rooting at the nodes and growing in patch.
Roots
White fibrous roots, fasciculate, also present at the nodes in contact with the soil.
Stem
Aerial stems are cylindrical, thick and lightly pubescens. Underground stems are white, essentially fertile and thinner than aerial ones.
Leaves
Simple alternate leaves, ovate to lanceolate, hairy, pale green, maximum 8cm long and 5cm wide with parallel veins. The base narrow into a petiole; petioles of 0.6cm long, Membranous leaf sheath, cylindrical with long red hairs. Pilosity variable, more important on the margin of the lamina (short one cell hairs and scales of 0.5mm). Inflorescence
Bracts subtending 3 to 4 flowers (spathe) fused at the base, funnel-shaped, about 1.5cm long and wide shortly pedunculate; external surfaces of the spathe with white hairs. The first flower is long-peduncled, the others sessile. Flowers lilac or blue, 2 lateral petals well visible and rounded and a central one very reduced. The plant has white, burrowing rhizomes which can produce subterranean flowers and seeds. It may be distinguished from other blue-flowered species by the short flower stalk which does not extend above the spathe margins, light colour, and by the reddish brown hairs on the leaf sheath. Both flower types are bisexual and self-pollinated.
Fruit
Capsule 3-lobed (2 anterior lobes dehiscent with 2 small seeds; 1 posterior lobe indehiscent with one big seed). 1 to 4 fruits by aerian spathe; only one by underground spathe.
Seeds
5 seeds by capsule. Dark brown, ellipsoidal in shape, trunqued. The smaller 2.5mm long, the biggest one 4mm long.
Seedling
First leaves elliptic, 3cm long and 2cm wide, base attenuated into a petiole. Undulated margin, pubescent lamina and parallel nerves.
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. Commelina benghalensis differ from Commelina diffusa by the presence of red hairs at the margin of leaf sheath, by the bracts funnel-shaped, fused and hairy, and by the sessile flowers.
- Merlier H., Montégut J. 1982. Adventices Tropicales. Flore aux stades plantule et adulte de 123 espèces 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.
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