In very rocky and muddy areas, grasses are scarce or disappear and creeping or cushioned camphytes and shrunken hemicryptophytes are often found, sometimes accompanied by stunted nanophanerophytes (Zapater, 1985).In depressions and ravines where water accumulates more or less permanently, the open plains are covered with a carpet of reeds, Cyperaceae and grasses (Cabrera, 1976).