Vegetative and reproductive growth of hluebunch wheatgrassin interior British Columbia has been documented for a Iyear period. Plants began growing immediately after snow melt in the spring, with measurable growth occurring where soils had warmed to 6 f 0.5’ C at lkm depths. Growth ceased from 7 May to 15 July and plants fully matured from 7 July to 10 August with actual dates for each particular site being dependent upon the local microclimate. Fall regrowth was not predictable, occurring only during 1973. Seed production was erratic, unpredictable from our data, and not of sufficient magnitude to sustain the grass population if improper grazing is allowed. Bluebunch wheatgrass (Agropyron spicutum) was the major plant species of the pristine vegetation complex of dry areas from the Canadian Rockies south to the mountain ridges of Mexican Sonora and from the Cascades east to the short-grass prairies (Harris 1967). In British Columbia, this species was the dominant plant on 1,295,OOO ha of rangeland in climax condition, contributing 95% of the total yield of herbage from the AgropyronArtemisiu community, 74% of the total yield from the Agropyron-Poe community, and 34% of the total yield from the Agropyron-Festuca community (Tisdale 1947). In the northwest, bluebunch wheatgrass is of considerable economic importance. As the dominant species on excellent condition ranges, it furnishes spring-fall and often winter grazing for livestock which are a principal industry of the region. If resource managers are to manage the range effectively and maintain sustained optimal production of livestock, they must have an understanding of the key forage species. Because of this, bluebunch wheatgrass has received considerable ecological (Heady 1949, Harris 1969, Benson 1973, Stocker 1975, Daubenmire 1978), manageAuthors are range scientist, range ecologist, and forage physiologist. Agriculture 0z+da, Range Research Station, 3015 Ord Road, Kamloops, B.C., Canada V2B This report is Agriculture Canada Rcs. Sta. Kamloops, B.C., Ms. 6230. Manuscript received April IS, 1980. 46 ment (Branson 1956, Wilson et al. 1966, Mueggler 1975, Blaisdell and Pechanec 1949, Rickard et al. 1975, Hormay and Talbot 1961, and others) and physiological (Mcllvanie 1942, Anderson and McNaughton 1973, DePuit 1975) attention. Despite numerous general descriptions, there have been few direct attempts to fully document the phenological development (Sauer and Uresk 1976, Blaisdell and Pechanec 1949) of bluebunch wheatgrass or to explain its growth development (Hyder and Sneva 1963). In all cases, the researcher has to assimilate pieces of information on these two topics from articles concerned with other facets of the autecology of this grass. In this paper, we describe phenology and reproductive growth of bluebunch wheatgrass at two locations in the southern interior dry belt of British Columbia, an area where scant information about the species is available.