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

122. Eriogonum twisselmannii (J. T. Howell) Reveal in P. A. Munz, Suppl. Calif. Fl. 40. 1968.

Twisselmann's wild buckwheat

Eriogonum douglasii Bentham var. twisselmannii J. T. Howell, Leafl. W. Bot. 10: 13. 1963

Herbs, matted, occasionally polygamodioecious, (0.2-)0.5-1.5 × 3-4 dm, tomentose. Stems: caudex spreading; 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, (0.2-)0.5-1.2 dm, tomentose, with a whorl of 4-8 leaflike bracts ca. midlength, similar to leaf blades, 0.4-0.8 × 0.1-0.3 cm. Leaves in loose to congested basal rosettes; petiole 0.2-0.4 cm, thinly tomentose; blade oblanceolate to elliptic, 0.5-1 × (0.2-)0.4-0.6 cm, white- or grayish-tomentose abaxially, thinly tomentose to nearly glabrous and dull green adaxially. Inflorescences capitate, 0.7-1.5 cm wide; branches absent; bracts absent immediately below involucre. Involucres 1 per node, campanulate, (2.5-)4-5 × 4-6 mm; teeth 6-9, lobelike, strongly reflexed, (2-)3-5 mm. Flowers (4-)5-6 mm, including 1-1.3 mm stipelike base; perianth pale yellow, villous abaxially; tepals slightly dimorphic, those of outer whorl obtuse, 3-5 × 3-3.5 mm, those of inner whorl broadly oblanceolate, 5-6 × 2.5-3 mm; stamens exserted, 4-5 mm; filaments pilose proximally. Achenes light brown, 5-5.5 mm, glabrous except for sparsely pubescent beak.

Flowering Jun-Sep. Rocky outcrops, montane conifer woodlands; of conservation concern; 2300-2600 m; Calif.

Eriogonum twisselmannii is a rare species of the southern Sierra Nevada and is known only from Slate Mountain and The Needles in Tulare County. It is worthy of being on a “watch” list of rare plants in California, but because of its remote location, it is not threatened.


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