Preliminary survey of root aerenchyma in Tripsacum

Thsacu?n plants of the species dactploides (eastern gamagrass) have been observed to withstand flooded soil conditions and roots of this species have been observed to penetrate deep into heavy clay soils. One commonality between these conditions is the low oxygen environment surrounding the roots due to water logging or soil compression. In both cases, the presence of aerenchyma in T. dactyloides roots may have ameliorated the adverse impact of the low oxygen environment. Previously, we have found that some T. dactyloides accessions exhibit well-formed root aerenchyma even under well-aerated, non-stress environments which may allow a competitive advantage for this species in adapting to a wide range of habitats. In this survey of root anatomy, 15 of 16 species of Tripsacion were evaluated to determine the extent to which aerenchyma occur in a well-aerated, non-stress environment. Among the 15 species, 26 accessions were surveyed. In only five of the 15 species were large, well-formed aerenchyma found. This indicates that the ability to forni aerenchyma under well-aerated, nonstress environments is not a universal adaptive mechanism within the genus and indicates the possibility of developing additional supraspecific groups based on root characteristics.