LEAF CROSS-SECTIONS AND PHYTOGEOGRAPHY - A POTENT COMBINATION FOR IDENTIFYING MEMBERS OF FESTUCA SUBGG FESTUCA AND LEUCOPOA (POACEAE), OCCURRING IN NORTH-AMERICA

Icon-like diagrams are used to summarize the anatomical patterns obser ved in leaf cross sections of 30 taxa of Festuca subgg. Festuca and Le ucopoa occurring in western North America. Measurements of four variab les, notes on the degree of development and the position of sclerenchy ma, along with distribution maps of 24 native taxa, are presented. Twe nty-nine diagrams were created from the synthesis of at least ten leaf -section drawings based on five plants chosen from across the geograph ic range of each taxon (fewer suitable specimens were obtained for two taxa). A key based on data collected in this study allows identificat ion of species in subg. Festuca. Geographic distribution is more relia ble than leaf anatomy for separating taxa in subg. Leucopoa.