| stomatal characteristics of riparian poplar species in a semi-arid environment. | several native poplar species meet at the margins of their natural distributions in southern alberta, canada. in this semi-arid area, poplars are obligate riparian species but they occupy several intergrading ecoregions. populus deltoides bartr. ex marsh predominates in the warmest and driest eastern prairie ecoregions; p. balsamifera l. occupies the cooler and wetter western parkland and montane ecoregions; and p. angustifolia james and hybrids between the species occur in the intermediate gras ... | 2006 | 16356918 |