113. Eriogonum congdonii (S. Stokes) Reveal, Aliso. 7: 220. 1970.
Congdon's wild buckwheat
Eriogonum ursinum S. Watson var. congdonii S. Stokes, Eriogonum, 114. 1936 (as congdoni); E. ternatum Howell var. congdonii (S. Stokes) J. T. Howell
Subshrubs, spreading to erect, synoecious, 1.5-5 × 1-3 dm, floccose or glabrous. Stems: caudex spreading to somewhat erect; aerial flowering stems erect, slender, solid, not fistulose, arising at nodes of caudex branches and at distal nodes of short, nonflowering aerial branches, 1-2(-2.5) dm, thinly floccose or glabrous. Leaves in rather compact basal rosettes; petiole 0.2-0.8 cm; blade narrowly elliptic to narrowly oblong, 0.5-2 × 0.3-0.6(-0.8) cm, densely white-tomentose abaxially, thinly floccose or glabrous and olive green adaxially, margins entire, revolute. Inflorescences umbellate, 0.3-3 × 1-3.5 cm; branches thinly floccose or glabrous; bracts 3-4, semileaflike, lanceolate, 0.1-0.5 × 0.1-0.3 mm. Involucres 1 per node, turbinate, 5-6 × 3-4 mm, tomentose; teeth 6-8, erect, 0.5-2 mm. Flowers 4-6 mm, including 0.4-0.6 mm stipelike base; perianth sulphur yellow, glabrous; tepals monomorphic, obovate; stamens exserted, 4-5 mm; filaments pilose proximally. Achenes light brown, 4-5.5 mm, glabrous except for sparsely pubescent beak.
Flowering Jul-Sep. Gravelly serpentine slopes and outcrops, manzanita communities, montane conifer woodlands; (1000-)1500-2300 m; Calif.
Eriogonum congdonii is an elegant subshrub restricted to the mountains of central-northern California (southern Siskiyou and northern Trinity counties). It is worthy of serious consideration as a garden introduction even though it typically occurs on nearly raw, greenish-black serpentine outcrops. In that setting, the olive green leaf blades, the bright green and nearly glabrous flowering stems and inflorescence branches, and the dense clusters of rich sulphur-yellow flowers make a beautiful contrast.