“…STERX has described both genetically fixed and plastic variation in a range of characters and related these in some cases to the habitat requirements of the two species.The second example, the annual species of the genus SaZicoz~ia L., has been less well studied. '[TLe observation that the generally little-branched, long-spiked tetraploid species and the well-branched, short-spiked diploid species have an overlapping but somewhat differential ecological distribution, the former being gene--rally found in lower pioneer znnes and the latter in more mature salt marsh, has been made by a number of authors (DALBY, 1962;BAKKER, TER BORG and OTZEN, 1966). An experimental investigation of this situation on the tetraploid S.dolie~ostuc~yu Moss and the diploid S.etmopuea L.…”