Great Basin Naturalist


Recent taxonomic studies in Mimulus support the recognition of Mimulus evanescens, a new autogamous species morphologically allied with M. breviflorus and M. latidens. Initially known only from herbarium specimens, the most recent from 1958, M. evanescens was relocated in the field in 1990 in northern Lassen Co., CA. A second population was found in southern Lake Co., OR, in 1993. Mimulus evanescens is apparently confined to the Great Basin and its periphery, where it has been recorded from 10 localities across Idaho, Oregon, and California. Based on collection information and visits to the two extant populations, the new species appears to be restricted to vernally moist sites and fluctuating banks of intermittent streams or pools. Long-term utilization of such sites by livestock may have contributed to the present-day rarity of M. evanescens. The species should be added to federal and state lists of candidate endangered species pending the results of future field studies and surveys.