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Benghal Dayflower, Tropical Spiderwort - Commelina benghalensis L.
Federal Noxious Weed Inspection Guide. USDA APHIS PPQ. Prepared by Randy Westbrooks, Whiteville, NC. September 1991.
Diagnostic Characteristics: Annual or perennial herb; stems creeping or ascending, succulent 15-40 cm long, branched, rooting at the nodes; leaves alternate, ovate to elliptic, sheaths often with red hairs at the apex; bracts subtending the flower funnel-shaped; Aerial flowers lilac or blue, petals 3-4 mm long; subterranean flowers whitish, cleistogamous, arising from basal shoots; fruit a capsule with two seeds; seeds ribbed, grayish-brown, 2 mm long.
This species may be distinguished from other blue-flowered species of the genus by the short flower stalk which does not usually extend above the spathe, and by reddish brown hairs on the leaf sheaths. (Ivens, 1967).
Basis as a Federal Noxious Weed: Competes with and reduces yields of a variety of crops and pasture species.
Habitat: A weed of moist places, roadsides, waste places, along dikes, on banks of irrigation ditches, in cultivated fields, around field borders, in wet pasturelands, gardens (Reed, 1977).
World Distribution: Angola, Australia, Brazil, Burma, China, Cuba, Ethiopia, Gambia, Ghana, Guinea, Guam, Hong Kong, India, Indonesia, Ivory Coast, Jamaica, Japan, Kenya, Korea, Madagascar, Malawi, Malaysia, Mali, Mauritius, Mozambique, Nepal, New Caledonia, New Guinea, Nigeria, Pakistan, Paraguay, Philippines, Rwanda, Saudi Arabia, South Africa, Senegal, Somalia, Sri Lanka, Sudan, Swaziland, Taiwan, Tanzania, Thailand, Uganda, United States (Florida and Hawaii), Vietnam, Zambia, Zimbabwe.
Plant Parts Likely to be Intercepted: Seeds, stolons.
Suggested Avenues of Entry into the United States: As a contaminant of seeds, spices and other condiments; as a general hitchhiker.
Notes: Benghal dayflower is an alternate host of the nematode Meloidogyne incognita (Valdez, 1968) and the groundnut rosette virus (Adams, 1967; Holm et al., 1977). The plant reproduces by seeds and stolons. One plant can produce as many as 1600 seeds (Pancho, 1964). Mechanical control of the plant is usually ineffective because broken pieces of the stem readily root at the nodes and continue growing. Many herbicides are ineffective against the weed. This is because the seeds continue to germinate after the first flush of summer weeds and because seeds are produced aerially and subterraneously as well (Budd et al., 1979).
Important Literature References:
Adams, A. 1967. The vectors and alternate hosts of groundnuts rosette virus in Central Province, Malawi. Rhodesian, Zambian, Malawian J. of Agr. Res. 5:145-151.
Bogdan, A. 1966. Weeds in herbage seeds in Kenya. East Afr. J. For. 32:63-66.
Budd, G., P. Thomas and J. Allison. 1979. Vegetative regeneration, depth of germination and seed dormanvy in Commelina benghalensis L. Rhod. J. Agr. Res. 17:151-153.
Hafliger, E. and H. Scholz. 1980. Grass Weeds 1. Weeds of the Subfamily Panicoideae. Ciba-Geigy, Ltd., Basel, Switzerland. 123 pp. plus illustrations.
Henderson, M. and J. Anderson. 1966. Common Weeds in South Africa. Botanical Survey, Memoir No. 37. Bot. Res. Inst., Dept. of Agr. Technical Services, Republic of South Africa. 440 pp.
Ivens, G. 1967. East African weeds and their control. Oxford Univ. Press. Nairobi. 244 pp.
Ivens, G. 1971. East African Weeds and Their Control, 2nd Ed.. Oxford Univ. Press. Nairobi. 250 pp.
Joshi, N. and S. Singh. 1965. Weeds of agriculture: Review of world literature. Agr. Res. Center, London. 296 pp.
Pancho, J. 1964. Seed sizes and production capacities of common weed species in rice fields of the Philippines. Phil. Agr. 48:307-316.
Reed, C. 1977. Economically Important Foreign Weeds. Potential Problems in the United States. U.S. Dept. of Agr. Agr. Handbook No. 498. 746 pp.
Terry, P. and R. Michieka. 1987. Common Weeds of East Africa. Food and Agriculture Organization of the United Nations. Rome. 184 pp.
Valdez, R. 1968. Survey, Identification and Host-parasite Relationships of Root-knot Nematodes Occurring in Some Parts of the Philippines. Phil. Agr. 51:802-824.
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Last updated on Wednesday, November 05, 2003 at 01:31 PM
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