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

96. Eriogonum strictum Bentham, Trans. Linn. Soc. London. 17: 414. 1836.

Herbs, erect, loosely to densely matted, not scapose, 1-5 × 1-10 dm, tomentose or glabrous. Stems spreading to erect, with or without persistent leaf bases, up to 4 height of plant; caudex stems absent or spreading to matted; aerial flowering stems erect to spreading, slender, solid, not fistulose, 1-3 dm, tomentose or glabrous.  Leaves basal, 1 per node; petiole rarely twisted or curled, 1-6 cm, mostly tomentose; blade elliptic to ovate, 0.5-2.5(-4) × (0.3-)0.5-1.5 cm, lanate, tomentose to floccose on both surfaces, sometimes sparsely tomentose to floccose and greenish or floccose to subglabrous or glabrous adaxially, margins plane. Inflorescences umbellate-cymose to cymose, 1-20 × 3-25 cm; branches dichotomous, tomentose to floccose or less often glabrous; bracts 3, scalelike, triangular, 1-3 mm. Peduncles absent. Involucres 1 per node, rarely 2-5 per cluster, narrowly turbinate to turbinate-campanulate, 4-6 × 1.5-5 mm, tomentose or glabrous; teeth 5, erect, 0.5-1.3 mm. Flowers 3-5(-6) mm; perianth yellow or white to rose or purple, glabrous; tepals connate proximally, dimorphic, those of outer whorl elliptic to nearly orbiculate, 2-3 × 2-3 mm, those of inner whorl oblanceolate to oblong, 3-4 × 1-2 mm; stamens included to slightly exserted, 2-5 mm; filaments pilose proximally. Achenes light brown to brown, 3-3.5 mm, glabrous.

Varieties 4 (4 in the flora): w United States.

Eriogonum strictum, E. niveum, and E. ovalifolium form a complex of closely related species differing in leaf, inflorescence branching, and flower features. Variety proliferum appears to be the basal entity of the complex, approaching both E. niveum and E. ovalifolium var. pansum in its pubescence and branching pattern. Also, specimens of var. proliferum are sometimes difficult to differentiate from E. nudum var. oblongifolium. Careful observation, though, will permit well-made collections to be easily distributed among the individual species. An alternative taxonomy is to reduce all of the taxa to E. ovalifolium and recognize a series of subspecies and varieties. It is possible that additional study will show that E. strictum is sufficiently distinct from its tomentose to floccose counterparts to justify recognition of E. proliferum. In that case, both var. anserinum and var. greenei would be assigned to the latter species. Or, one could follow C. L. Hitchcock et al. (1955-1969, vol. 2) and recognize subsp. strictum as distinct from subsp. proliferum, with the latter consisting of varieties proliferum, anserinum, and greenei.

Members of the Eriogonum strictum are food plants for the Bauer's dotted-blue butterfly (Euphilotes baueri).

1 Inflorescence branches glabrous   96d var. strictum
+ Inflorescence branches tomentose to floccose   (2)
2 (1) Perianths yellow   96c var. anserinum
+ Perianths white to rose or purple   (3)
3 (2) Leaf blades grayish-tomentose to floccose on both surfaces, or greenish-tomentose to floccose adaxially   96a var. proliferum
+ Leaf blades densely whitish-lanate to tomentose on both surfaces   96b var. greenei


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