Dedeckera (Polygonaceae), a new genus from California

A new genus and species,Dedeckera eurekensis, are described from the Last Chance Mountains, Inyo Co., California, from an area just south of the Eureka Valley sand dunes. A member of Polygonaceae, it is most closely related toEriogonum, differing from that genus in lacking a tubular involucre, and fromStenogonum, Hollisteria, Nemacaulis, andGilmania in being a shrubby perennial. It differs from all other members of the subfamily Eriogonoideae in having (1) a head of subsessile or sessile flowers borne on a slender peduncle and subtended by 2 to 5 foliaceous bracts, and (2) a single short-pedicellate axillary flower at the base of each peduncle. The numerous yellow-flowered heads are arranged in open cymose inflorescences that terminate short annually produced branches with alternately arranged exstipulate foliage leaves.Eriogonum flexum is transferred to the genusStenogonum. A key to the genera of subfamily Eriogonoideae is included.