Ageratina riparia (PROSEA)
Ageratina riparia (Regel) R.M. King & H. Robinson
- Family: Compositae
- Eupatorium harrisii Urban,
- E. riparium Regel.
- Mist flower, creeping crofton (En), hamakua pamakini (Hawaii) (Am)
- Indonesia: teklan (Sundanese).
Native to Mexico and the West Indies, now widely distributed in South-East Asia, Indo-China, India, Sri Lanka, Australia and Hawaii.
A. riparia was spread mainly as an ornamental but has become a troublesome weed in Java, Thailand, India, Sri Lanka, Australia and Hawaii. In Java it is used as green material for composting, and as a cover crop to check erosion on slopes and terrace walls and the spread of Imperata cylindrica (L.) Raeuschel. Having strong antifungal properties it is used medicinally in Java and Sri Lanka. In southern Queensland it is suspected of causing mortality in horses feeding on it, via lung lesions resulting in chronic eosinophilic bronchiolitis.
- Erect, perennial shrub or herb, 0.5-1.0 m tall, with creeping stems, rooting at the nodes, hairy, becoming glabrous near the base.
- Leaves opposite; petiole 0.5-2.0 cm long, blade elliptical-lanceolate, 2-10 cm × 0.5-2.5 cm, margins sharply serrate in the upper part, nearly glabrous above, sparsely hairy beneath.
- Inflorescence a 12-15-headed, paniculate corymb; heads 15-20-flowered.
- Flowers white, corolla 3.0-3.5 mm long, 5-lobed.
- Fruit an achene, linear-oblong, 1.5-2.0 mm long, 5-ribbed, ribs pubescent, narrow at the top, black.
A. riparia occurs in South-East Asia between (250-)1000-2500 m altitude in shaded, humid locations, along watercourses and field boundaries, on slopes, in tea plantations and forest clearings. It is damaged by frost. It may produce up to 100 000 seeds per plant per year and 75% of fresh seed may germinate within a week. Germination is promoted by light and inhibited by burial. In some wet highland areas it has spread into pastures and reduced their carrying capacity considerably. A. riparia has allelopathic effects on crops. It is difficult to kill using herbicides only, but it can be controlled by brushing, followed by spraying with a herbicide, burning the area and sowing a leguminous cover crop. Biological control using white smut (Entyloma ageratinae) has been effective at 500-2000 m altitude in Hawaii.
- Anthonsen, T., 1969. New chromenes from Eupatorium species. Acta Chemica Scandinavica 23: 3605-3607.
- Charudattan, R. & DeLoach, C.J., 1988. Management of pathogens and insects for weed control in agroecosystems. In: Altieri, M.A. & Liebman, M. (Editors): Weed management in agroecosystems: ecological approaches. CRC Press, Roca Baton, United States. pp. 245-264.
- Dassanayake, M.D. & Fosberg, F.R. (Editors), 1980-. A revised handbook to the flora of Ceylon. volume 1-. Amerind Publishing Co., New Delhi, India.
- Koster, J.T., 1935. The Compositae of the Malay archipelago. 1. Vernonieae and Eupatorieae. Blumea 1: 351-536.
- Taylor, D.R. & Wright, J.A., 1971. Chromenes from Eupatorium riparium. Phytochemistry 10: 1665-1667.
- Yadav, A.S. & Tripathi, R.S., 1982. A study of seed population dynamics of three weedy species of Eupatorium. Weed Research 22: 69-76.
- M.S.M. Sosef & L.J.G. van der Maesen