Adaptations ofStipagrostisspecies to desert dunes

Four ecomorphological types are recognised in the ‘Old World’ genusStipagrostis: (1) species confined to areas of high sand mobility, which require accumulating sand cover for survival; (2) species of sandy areas which may be covered with sand or the sand may be removed; (3) species confined to stable or slightly eroding sand sheets; and (4) annual species of areas with less than 50 mm rainfall annually. Most species have a plumose diaspore which glides easily over long distances. Diaspores of a few species have a pappose awn, and are dragged on the dune surface to a leeward slope where they are covered by sand.