The Allelopathic Effects Of Yaupon On Associated Herbaceous Species

Abstract

A field survey showed a definite decrease in species diversity of herbaceous vegetation beneath yaupon (Ilex vomitoria) canopy in comparison to vegetation in open areas between yaupon clumps. Several laboratory experiments were performed to test the possibility of inhibition due to excretion of toxic substances by yaupon into the environment. The effects of aqueous extracts from plant materials and associated soils on germination and initial growth of cucumber (Cucumis sativus L.) and wheat (Triticum aestivum L.) were studied. The following materials were collected from mature yaupon stands for use in aqueous extract preparation: fresh yaupon leaves, leaf litter, yaupon roots, soil from within a yaupon canopy, soil from an open, grassy area, and yaupon berries. Strong inhibition of test seed germination and growth did not occur in potting dishes when water extracts were applied: There was no significant difference in germination or growth in leaf and stem of the test subjects after treatment with extract solutions when compared with the controls; there was no apparent difference among the extracts obtained from the various yaupon plant parts or soils.