Illustrated Flora of the Pacific States

Abstract

THE region of the Pacific States with which the book under review deals is of great interest to the student of geographical distribution and the taxonomist. The area is peculiarly rich in endemic genera and species, and this is especially true of California. The Pacific States show interesting geographical connexions with the flora of Eastern Asia in genera, however, which are probably too recent in origin to be adduced in support of any hypothesis of continental drift, but are to be regarded rather as evidence of the similarity of ecological conditions and the high efficiency of dispersal agents, not perhaps excluding man himself. Thus the saxifragaceous species Leptarrhena pyrolifolia is native both to the coastal regions of north-west America and to eastern Asia. Again, the genus Pectiantia comprises five species of which three are endemic to the Pacific States, whereas the other two are natives of Japan. But it is in the endemics of the region that the chief interest of the flora rests. Some of these, such as Romneya Coulteri, the genera Eschscholtzia and Lewisia, are familiar to British horticulturists. In the family Polygonaceae the monotypic genera Gilmania, Nemacaulis and Hollisteria are all endemic to California while of the 150 known species of Eriogonum 80 are found in the Pacific States, many of them endemic. In the Crassulaceæ there are some 35 endemic species belonging to the genera Sedella, Budleya, Stylophyllum, Hasseanthus and Gormania. In the Cruciferse most of the species of Thelypodium, Streptanthus and Caulanthus are endemic. The Rosacese, too, provide a large number of endemics, particularly in the genera Horskelia (19 spp.) and Ivesia (17 spp.). In the Leguminosse the outstanding genera in this respect are Lupinus, of which 58 species are probably endemic, Hosackia, of which most of the 39 species are endemic, while Astragalus is represented by 137 species of which 83 are probably endemic.

Illustrated Flora of the Pacific States

Washington, Oregon and California. By Leroy Abrams. In 4 vols. Vol. 2: Polygonaceae to Krameriaceae, Buckwheats to Kramerias. Pp. viii + 635. (Stanford University, Calif.: Stanford University Press; London: Oxford University Press, 1944.) 45s. 6d. net.