Umtanum Desert wild buckwheat

Herbs, matted, not scapose, 0.3-1 × (1-)2-7(-9) dm, tomentose, greenish. Stems matted, with persistent leaf bases, up to 4 height of plant; caudex stems matted; aerial flowering stems erect, slender, solid, not fistulose, 0.2-0.9 dm, floccose.  Leaves basal, fasciculate in terminal tufts; petiole 0.2-0.8(-1) cm, tomentose; blade oblanceolate to elliptic, (0.5-)0.6-1.2 × 0.3-0.6 cm, densely white-tomentose on both surfaces, margins plane. Inflorescences cymose-umbellate or cymose, 1-2 × 1-4 cm, tomentose; branches dichotomous, floccose; bracts triangular, scalelike, 1-2.5 mm. Peduncles erect, slender, (0.15-)0.2-0.5(-0.7) cm, floccose. Involucres 1 per node, turbinate-campanulate, 2.5-4 × 2-2.5 mm, membranous, tomentose to floccose; teeth 5, erect, 0.8-1.2(-1.5) mm. Flowers 2-3 mm; perianth lemon yellow, thinly tomentose; tepals connate proximal 1/ 2, monomorphic, broadly oblong to oblong; stamens slightly exserted, 2.5-3.5 mm; filaments sparsely pilose proximally. Achenes light brown, 2.5-3 mm, sparsely tomentose.

Flowering May-Aug. Gravelly volcanic soils, mixed grassland, saltbush and sagebrush communities; of conservation concern; 300-400 m; Wash.

Eriogonum codium is a potentially endangered species known from a single site on volcanic bluffs overlooking the Columbia River in Hanford Research National Monument in Benton County. It is worthy of cultivation as a rock-garden plant, although little or no sexual reproduction is known in the natural population. The Umtanum Desert wild buckwheat is a candidate for federal listing and is considered an endangered species by the state of Washington. Much of the population was destroyed in a man-caused fire in 1997. The species is in the Center for Plant Conservation's National Collection of Endangered Plants.