FACTORS INFLUENCING SEED IMBIBITION OF BLACKBRUSH (COLEOGYNE RAMOSISSIMA: ROSACEAE)

Intraspecific variation in blackbrush (Coleogyne ramosissima) seed imbibition was investigated using seeds collected at elevations of 1,100 and 1,700 m in the Spring Mountains, Clark County, Nevada. Under experimental conditions in the laboratory, seeds of C. ramosissima collected Bout a high-elevation site imbibed more water than seeds collected from a low-elevation site. Amount of water in seeds at full imbibition was not affected by mode of wetting and age of seed. Thickness of testa, a possible source of regulation of imbibition, also did not differ between collection sites. These results suggest that imbibition potential of scents of C. ramosissima may differ as a function of elevation, a trait with potential adaptive importance for this dominant aridland shrub.