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We examined the distribution of herbaceous species in southern Wisconsin floodplain forests in relation to two major environmental factors: elevation and light. Most species had definite elevation optima and could be categorized as either light specialists for high or low light, or light generalists. To test Grime's ideas regarding the existence of three primary plant strategies (competitive, stress tolerant, and ruderal), we used simple autecological indices to classify species into guilds. Higher elevation areas were dominated by tall competitive perennial forbs. As flooding frequency increased, smaller perennial forbs (stress-tolerant competitors) and tall annuals (competitive ruderals) increased in importance. In areas of greatest flooding frequency, the dichotomy in plant strategies was most extreme: slowgrowing, flood-tolerant sedges and grasses (stress tolerators) shared the ground with small, fast-maturing, annual forbs …