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FNA | Family List | FNA Vol. 5 | Polygonaceae | Eriogonum

126. Eriogonum incanum Torrey & A. Gray, Proc. Amer. Acad. Arts. 8: 161. 1870.

Frosted wild buckwheat

Eriogonum marifolium Torrey & A. Gray var. incanum (Torrey & A. Gray) M. E. Jones; E. ursinum S. Watson var. rosulatum (Small) S. Stokes

Herbs, matted, dioecious, 0.5-3 × 1-4 dm wide, tomentose to floccose. Stems: caudex spread-ing; aerial flowering stems erect or nearly so, slender, solid, not fistulose, arising at nodes of caudex branches and at distal nodes of short, nonflowering aerial branches, 0.1-2(-2.5) dm, tomentose to floccose. Leaves in loose to congested basal rosettes; petiole (0.3-)0.5-1 cm, tomentose; blade oblong to oblong-ovate or spatulate, 0.5-1.5 × 0.3-0.7 cm, densely white- or grayish-tomentose on both surfaces, sometimes greenish adaxially, margins entire, plane. Inflorescences capitate and 0.5-2 cm wide, mature pistillate plants open and umbellate, 1-3 × 1-4 cm; branches tomentose to floccose; bracts 2-6, leaflike, 0.1-0.5 × 0.1-0.3 cm, often absent immediately below involucre. Involucres 1 per node but occasionally appearing congested, turbinate-campanulate, 2.5-3 × 2-2.5 mm, tomentose; teeth 5-8, erect, 0.5-1 mm. Flowers stipelike base 0.5-1 mm; perianth yellow, glabrous; staminate flowers 2-3 mm, tepals ovate; pistillate flowers 4-6 mm, tepals oblanceolate, often becoming reddish in fruit; stamens exserted, 2-3 mm; filaments pilose proximally. Achenes light brown to brown, 3-3.5 mm, glabrous except for sparsely pubescent beak.

Flowering Jun-Sep. Sandy to gravelly or rocky granitic or occasionally volcanic flats, slopes, and outcrops, mixed grassland, manzanita, and sagebrush communities, montane conifer woodlands; (1900-) 2100-4000 m; Calif., Nev.

Eriogonum incanum is common throughout the central and southern Sierra Nevada of California (Alpine, El Dorado, Fresno, Inyo, Madera, Mariposa, Nevada, Tulare, and Tuolumne counties) and extreme west-central Nevada (Carson City, Douglas, and Washoe counties). It is a food plant for the green hairstreak butterfly (Callophrys lemberti), the Pacific dotted-blue (Euphilotes enoptes), and the gorgon copper (Gaeides gorgon).


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