Ecology of Parthenium

In India, it is noticed only from mid-fifties and is presumed to have been accidentally introduced by the import of wheat in Maharashtra during 1956. However, it's spread throughout the country has been very rapid with abnormal density. Further, factors such as (i) the absence of natural agents that restrict the spread of this plant, (ii) high fecundity, (iii) efficient seed dispersal mechanisms, (iv) Allelopathy impact on other plant species, (v) unsuitability for grazing because of the presence of anti-feedants in the plant system and (vi) wide adaptability to varying soil and agro climatic conditions have enabled this plant to invade a variety of growing environments particularly in situations associated with human activities.