3. Stenogonum Nuttall, Proc. Acad. Nat. Sci. Philadelphia. 4: 19. 1848.
Two-whorl buckwheat [Greek stenos, narrow, and gonos, seed, alluding to achene]
James L. Reveal
Eriogonum Michaux sect. Stenogonum (Nuttall) Kuntze
Herbs, annual; taproot slender. Stems arising directly from the root, spreading to decumbent, solid, not fistulose or disarticulating into ringlike segments, glabrous or minutely strigose or glandular. Leaves usually persistent through anthesis, basal and rosulate or basal and cauline, alternate; petiole present (basal leaves); blade narrowly lanceolate to oblanceolate or spatulate to orbiculate, margins entire. Inflorescences terminal, cymose; branches mostly dichotomous, not brittle or disarticulating into segments, round, minutely strigose or glandular, glabrous; bracts 3 per node, connate basally, scalelike, triangular, not awn-tipped, glabrous or sparsely glandular. Peduncles straight or flexed, slender to filiform, sometimes absent. Involucral bracts in 2 whorls of 3, connate proximally, lanceolate, not awn-tipped. Flowers (6-)9-15 per involucral cluster at any single time during full anthesis; perianth yellow to reddish yellow, broadly campanulate when open, narrowly urceolate when closed, pilose abaxially; tepals 6, monomorphic, entire apically; stamens 9; filaments basally adnate, glabrous; anthers yellow, oval. Achenes usually included, light brown, not winged, 3-gonous, glabrous. Seeds: embryo curved. x = 20.
Species 2 (2 in the flora): w United States.
Stenogonum is clearly allied to Eriogonum subg. Ganysma, specifically E. trichopes and its close relatives. The genus is readily distinguished from Eriogonum by an involucre reduced to a series of two foliaceous whorls of three lanceolate bracts.
SELECTED REFERENCE
Reveal, J. L. and B. Ertter. 1977. Re-establishment of Stenogonum (Polygonaceae). Great Basin Naturalist 36: 272-280.
