107q. Eriogonum umbellatum Torrey var. dichrocephalum Gandoger, Bull. Soc. Roy. Bot. Belgique. 42: 199. 1906.
Bicolor sulphur flower
Eriogonum latum Small ex Rydberg; E. umbellatum subsp. aridum (Greene) S. Stokes; E. umbellatum var. aridum (Greene) C. L. Hitchcock
Herbs, spreading (rarely compact) mats, 1-3(-3.5) × 5-10 dm. Aerial flowering stems erect (rarely spreading), (0.5-)1-2.5 dm, thinly tomentose to floccose or rarely glabrous, without one or more leaflike bracts ca. midlength. Leaves in mostly loose rosettes; blade elliptic to broadly elliptic, 1-2(-2.5) × 0.5-1.5(-2) cm, tomentose to floccose abaxially, thinly tomentose or glabrous and green adaxially, margins plane. Inflorescences umbellate; branches 0.5-4 cm, thinly tomentose, without a whorl of bracts ca. midlength; involucral tubes 2-3 mm, lobes 1-2.5 mm. Flowers 4-8 mm; perianth pale yellow to cream or whitish, rarely greenish white.
Flowering Jun-Sep. Sandy to gravelly flats, slopes, and ridges, mixed grassland and sagebrush communities, pinyon and/or juniper and montane to subalpine conifer woodlands; (1200-)1400-3100(-3400) m; Calif., Idaho, Mont., Nev., Oreg., Utah, Wyo.
Variety dichrocephalum is widespread and occasionally locally common from southeastern Oregon, southern Idaho, western, and western Wyoming south to central-eastern California, central Nevada, and northern Utah.
In western Montana and Wyoming var. dichrocephalum is not always clearly distinct from var. majus, the key difference being that the tomentum of the former tends to be more whitish, while that of the latter is rusty. Furthermore, the adaxial surface of the leaf blades in the latter tends to be olive green, a color not seen in var. dichrocephalum. Finally, the leaves of var. majus tend to be longer and narrower, and the entire plant forms a flat, dense mat, a condition not usually seen in the more loosely arranged mats of var. dichrocephalum.