Alligator Weed in Indian Lakes

Abstract

Alternanthera philoxeroides (Mart.) Griseb., a South American weed of the family Amaranthaceae, has been found in the lakes and water pools in the eastern parts of India, namely, West Bengal and Bihar. This species was introduced long ago in the tropics of the Old World, but its introduction into India has taken place during late years. In 1875, Otto Kuntze found this species growing in the vicinity of Java, where it has now become established in stagnant or slow-moving water^1,2. In the Calcutta Herbarium there is a specimen from Victoria Lake in Rangoon district, Burma, collected in 1932 by C. E. Parkinson. This note is probably the first record of its occurrence on the Asiatic mainland. Apparently the species has made further ingress in Eastern India. Like several other American weeds, it seems probable that a few viable seeds of this species might have reached India along with some packing material during the Second World War. This is conceivable in view of the fact that this species was collected for the first time in India near an aerodrome at Calcutta. During recent years, a large number of neotropical weeds have been found to naturalize on Indian soil and spread like wildfire³. Further, in this species reproduction takes place vegetatively by means of subterranean shoots, and thus under favourable conditions it spreads rapidly, forming dense masses.