Observations on Natural Clones in Holcus Mollis

Summary Morphological examination of a group of fifty‐eight isolates of Holcus mollis from natural hill vegetation suggested that the collection was composed of four plant‐types only. Further experiments proved that there were major discontinuities between the plant‐types, and relatively little heterogeneity within them. It is argued that each plant‐type corresponds to a single colonizing seedling. Acceptance of this interpretation implies that natural stands of H. mollis contain very few genotypes, some of them replicated very many times, and this fits in with the presumed cytological history of the species. One of the genotypes observed was found in an area over half a mile across, in an ecological non‐uniform terrain, so that the actual migration route might have been much longer.