Invasive African grasses in south Texas: are they allelopathic?

Romeo G. Segura, Undergraduate Student Poster presentation

Authors: Fierro-Caba A., Mullins E., Segura R.

Affiliation School of Earth, Environmental, and Marine Sciences and Department of Biology. University of Texas Rio Grande Valley

Megathyrsus maximus (Guinea grass), Dichanthium annulatum (Kleberg bluestem) and Cenchrus ciliaris (Buffel grass) are common invasive grasses in the Tamaulipan thorn forest of southern Texas. These grasses were originally introduced as fodder, but have successfully established in disturbed habitats and have spread to areas in which they were not originally introduced. These grasses can reduce the fitness of native species by competing for resources such as space, water, light and nutrients; eventually dominating the community, preventing seedling recruitment or hindering reforestation efforts. Factors that contribute to the success of these species are not fully understood. A more complete understanding of these species could aid in efforts to reduce their presence.

The goal of this study is to test the allelopathic potential of these grasses to establish whether or not allelopathy could be a mechanism by which these grasses outcompete native species. Laboratory bioassays will be performed using aqueous extracts of the grasses against sensitive test species. Germination time and seedling elongation will be measured to establish potential allelopathic interference with the germination p1-ocess and initial growth of seedlings. Upon completion of this experiment there will be more information on these grasses and a better understanding of their success among native species.

Research is part of The Nature Conservancy’s Sabal Palm/Thornscrub Research Project funded by the Robert J. Kleberg, Jr. and Helen C. Kleberg Foundation.  For further information, contact Sonia Najera at