118. Eriogonum thymoides Bentham in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 9. 1856.
Thyme-leaf wild buckwheat
Eriogonum sphaerocephalum Douglas ex Bentham subsp. minimum (Small) S. Stokes; E. thymoides subsp. congestum S. Stokes
Subshrubs, spreading, polyga-modioecious, 0.5-2(-3) × 1-3(-4) dm, tomentose to sericeous. Stems: caudex spreading; aerial flowering stems erect, slender, solid, not fistulose, arising at nodes of caudex branches and at distal nodes of short, nonflowering aerial branches, (0.1-)0.3-0.8(-1.2) dm, tomentose to sericeous, with a whorl of 6-10(-12), leaflike bracts ca. midlength, these similar to leaf blades, 0.3-0.8(-1) × 0.1-0.2 cm. Leaves in compact basal rosettes, fasciculate, and sheathing up stems; petiole 0.05-0.2 cm; blade linear to narrowly spatulate, (0.2-)0.3-1(-1.5) × 0.1-0.2(-0.3) cm, densely white-tomentose abaxially, silky-villous or sericeous adaxially, margins entire, inrolled to tightly revolute. Inflorescences capitate, 0.8-2 cm wide; branches absent; bracts absent immediately below involucre. Involucres 1 per node, turbinate, 3-5 × 2.5-4 mm, villous to sericeous; teeth 6-8, erect, 0.5-1 mm. Flowers 4-10 mm, including 0.5-1 mm stipelike base; perianth white to pale yellow or yellow, becoming pink to rose, villous abaxially; tepals monomorphic, obovate; stamens included to slightly exserted, 2-4 mm; filaments pilose proximally. Achenes light brown, 2-2.5 mm, glabrous except for densely pubescent beak.
Flowering Apr-Jul. Sandy to gravelly, often volcanic flats, slopes, and outcrops, mixed grassland and sagebrush communities, montane conifer woodlands; (200-)600-1700 m; Idaho, Oreg., Wash.
Eriogonum thymoides is an exquisite species concentrated in three regions of the Pacific Northwest. The first is along the eastern edge of the Cascade Range from near Wenatchee, Washington (Adams, Benton, Chelan, Douglas, Franklin, Grant, Kittitas, Klickitat, Lincoln, and Yakima counties), to near the Dalles in extreme north-central Oregon (Union County). The second is from Baker and northern Malheur counties, Oregon, to Adams, Canyon, and Washington counties, Idaho. A third series of populations is in the Mount Bennett Hills area of Gooding County, Idaho, and just over the borders in Blaine, Camas, Elmore, and Lincoln counties. Staminate plants tend to have yellow flowers that quickly fade after pollen release. Pistillate plants tend to have white to pale yellow flowers that persist and greatly elongate as the achene matures.