In Arkansas, during seasonal drought periods, lake water levels drop leaving exposed mudflats which are primary sites for seedling establishment. Commonly, these exposed mudflats are partially covered with decomposing litter from previous stands of aquatic plants. In this study, aqueous leachates from the litter of four macrophytes, Eleocharis quadrangulata, Justicia americana, Polygonum lapathifolium, and Potamogeton nodosus, were used to test for chemical interference with germination and seedling growth. Only Justicia americana leachate was found to affect the growth of several of the test species. The potential for chemical interference by Justicia litter was evaluated further using extracts of acidified leachate. Resulting bioassays demonstrated significant effects on growth but not on seed germination. Bioassays of chromatographically separated fractions again revealed significant effects on seedling growth. These results suggest that interference by Justicia americana leachate on growth of seedlings is in part allelochemic.
Carter, Mark F.; Lane, Forrest E.; and Grace, James B.
"Effects of Litter on Aquatic Macrophyte Germination and Growth,"
Journal of the Arkansas Academy of Science: Vol. 39
, Article 9.
Available at: http://scholarworks.uark.edu/jaas/vol39/iss1/9