This paper honours the contribution of the E.S. Levy to the development of improved pasture plant cultivars in New Zealand by reviewing his work on ecotype development within herbage species. Starting in the late 19209, Levy compared at a single site many thousands of seed lines of pasture grass and legume species collected from both within New Zealand and overseas. In several species, including perennial ryegrass, white clover, red clover, cocksfoot and subterranean clover, he showed the existence of genetically distinct strains (ecotypes) which he claimed had developed under the farming practices, climate and soil fertility in their areas of origin. This work led to the enunciation of pasture plant breeding objectives, the development of improved pasture cultivars and a strategy for grassland improvement. This wes based on permanent pasture Hawke's Bay perennial ryegrass and New Zealand No. 1 white clover, bred for use in high production forage systems throughout New Zealand. The breeding objectives rejected by Levy, such as the development of improved cultivars for low production systems, must be reconsidered in view of today's changed environment for pastoral farming. Keywords: ecotypic differentiation, evolution, improved cultivars, plant breeding objectives.
