The Role of Soil in the Distribution of Four Grass Species in Texas

Abstract

The distributional patterns of Panicum virgatum L., Sorghastrum nutans (L.) Nash, Andropogon scoparius Michx. and Bouteloua curtipendula (Michx.) Torr. include a number of soil types in central and eastern Texas. Of six soil types studied, two were calcareous, two were acid and the remaining two were derived from serpentine and from granite. Clonal segments and seedlings grown on the soil types and subjected to certain nutrient elements showed that Panicum had a broad tolerance for the various edaphic conditions without evidence of being ecotypically differentiated. Andropogon plants from four areas showed a wide tolerance with slight selectivity in favor of calcareous soils. Andropogon plants from the acid pinewoods areas were susceptible to chlorosis on the calcareous soils, suggesting ecotypic differentiation due to edaphic conditions. Andropogon plants originating on calcareous soils were more tolerant than those from acid soils to high levels of calcium. Sorghastrum showed greatest response to serpentine and calcareous soils, but had a slight selectivity by some plants from acid soils for their native soils. Bouteloua plants, regardless of origin, grew best on the calcareous soils. A caespitose type of Bouteloua showed a selectivity for its native granitic soil and a rhizomatous type of Bouteloua showed a selectivity for its native calcareous soil. Both types of Bouteloua died when grown on acid soil from eastern Texas. Panicum virgatum, S. nutans, and A. scoparius, therefore, appear to have a wide tolerance for edaphic conditions with the exception of the eastern Texas populations of A. scoparius. The distribution of B. curtipendula is influenced, at least in part, by the presence of edaphic differentiation.