Marum-leaf wild buckwheat

Eriogonum cupulatum S. Stokes; E. marifolium var. apertum S. Stokes

Herbs, matted, dioecious, (0.1-)0.5-5 × 2-8 dm, floccose or glabrous. Stems: caudex spread-ing; aerial flowering stems erect, slender, solid, not fistulose, arising at nodes of caudex branches and at distal nodes of short, non-flowering aerial branches, (0.1-)0.5-4 dm, floccose or glabrous. Leaves in loose to compact basal rosettes; petiole 0.3-2 cm, often tomentose; blade ovate to oval, 0.3-3 × 0.3-1 cm, densely tannish- to brownish-lanate abaxially, glabrate and green to olive green adaxially, margins entire, plane. Inflorescences capitate, 0.5-2 cm wide, mature pistillate plants open and elongate-umbellate, 1-5 × 1-7 cm; branches usually glabrous; bracts 5-10, leaflike, 0.2-0.8 cm, often absent immediately below involucre. Involucres 1 per node but occasionally appearing congested, turbinate and 2-3 × 1.5-2 mm or campanulate and 4-5 × 5-7 mm, sparsely tomentose or glabrous; teeth 5-6, erect, 0.4-0.7 mm. Flowers stipelike base 0.5-1 mm; perianth yellow, glabrous; staminate flowers 1.5-3 mm, tepals ovate; pistillate flowers 4-7 mm, tepals oblanceolate, often becoming reddish in fruit; stamens exserted, 2-3 mm; filaments pilose proximally. Achenes light brown to brown, 3.5-5 mm, glabrous except for sparsely pubescent beak. 2n = 32.

Varieties 2 (2 in the flora): w United States.

Eriogonum marifolium is dioecious, with the two sexes having such markedly different morphology that collectors often consider each to represent a different species. In Oregon, male plants of E. marifolium and E. umbellatum var. haussknechtii can be difficult to distinguish. In El Dorado and Placer counties, California, herbarium specimens of E. marifolium and E. incanum can be difficult to separate, as their distribution ranges overlap there.