Growth and Flowering of Danthonia Sericea Populations

Seasonal growth and flowering in relation to environmental stimuli were studies in 20 populations of Danthonia sericea Nutt. ranging from New Jersey to Georgia. Flowering in the natural habitat was correlated (r = 0.988) with latitude, but New Jersey transplant and greenhouse tests indicated that populations of this species can be separated into three groups on the basis of their habitats and flowering response mechanism. Populations with glabrous sheaths from bogs or wet areas net to rivers of ponds in New Jersey required only adequate air and soil temperatures for growth and subsequent flowering. In these wet habitats substrate temperature apparently serves as the environmental stimulus to which the plants respond. For the populations with pubescent sheaths occurring at openings or fringes of upland pine—oak forest on well drained, sandy soils and for the glabrous populations occurring along stream borders and drainage areas adjacent to granite outcrops in Georgia, an additional requirement for specific photoperiods apparently exists.