sentences:  The historical range of "Trifolium amoenum" was from the western extreme of the Sacramento Valley in Solano County west and north to Marin and Sonoma Counties, where many sites were presumed extirpated by urban and agricultural development.From further expansion of the human population, "Trifolium amoenum" had become a rare species by the mid 1900s.Through the latter 1900s the number of distinct populations dwindled to about 20 in number, from pressure of an expanding human population and urban development.