Abstract
The paper deals with toxic effects of leaf leachate of Chromolaena odorata on Allium cepa. Leaf leachate impeded plant growth and decreased chlorophyll, protein and catalase contents. Cell division efficiency declines gradually with a concomitant distortion of the chromosomal conformity. Impaired cell division and chromatin structure seem to be the root cause of all other adverse effects. The reduction in catalase content made plants incompetent to eradicate free radicals that led their fast ageing.