Eriogonum rotundifolium |
Eriogonum annuum |
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round-leaf wild buckwheat, roundleaf buckwheat |
annual buckwheat, annual wild buckwheat |
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Habit | Herbs, spreading, annual, 0.5–4 dm, glabrous and often glaucous, greenish to grayish. | Herbs, 5–20 × 5–10 dm, grayish. |
Stems | caudex absent; aerial flowering stems erect, solid, not fistulose, 0.1–0.5(–0.7) dm, glabrous. |
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Aerial flowering stems | slender, 4–10(–15) dm, floccose to densely tomentose. |
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Leaves | basal; petiole 1.5–4 cm, floccose; blade cordate to orbiculate, 1–2(–3) × 1–2.5(–3) cm, densely white-tomentose abaxially, floccose or subglabrous and greenish adaxially, margins plane. |
petiole (rosette) 0.3–1.2 cm, or petiole (cauline) 0.2–0.5 cm, tomentose to floccose; blade oblanceolate to oblong, 1–7 × 0.3–1.5 cm, densely tomentose abaxially, floccose adaxially not thickened and auriculate-subclasping proximally; margins entire or slightly revolute. |
Inflorescences | cymose, open to diffuse, usually flat-topped, 5–35 × 5–35 cm; branches glabrous; bracts 3, scalelike, 1–2.5 × 0.5–2 mm. |
3–10 × 2–7 cm; bracts triangular, 1–4 mm. |
Peduncles | erect, straight, stoutish, 0.3–1.5 cm, glabrous. |
0.1–0.5 cm, tomentose to floccose. |
Involucres | turbinate to campanulate, 1–2 × 1.5–2.5 mm, glabrous; teeth 5, erect, 0.4–0.8 mm. |
turbinate to campanulate, 2.5–4 × 2–3 mm, tomentose to floccose abaxially, glabrous adaxially; teeth 5–6, 0.4–1 mm. |
Flowers | 1–2.5 mm; perianth white to pink with greenish to reddish midribs, becoming rose to red, glabrous; tepals dimorphic, those of outer whorl flabellate, those of inner whorl lanceolate; stamens included, 1.2–1.7 mm; filaments pilose proximally. |
1–2.5 mm; perianth white or cream to rose; tepals: those of outer whorl obovate, 1–2 × 0.9–1.5 mm, those of inner whorl narrowly ovate to oblong, 1.5–4 × 1.2–1.8 mm; stamens usually included, 1–2 mm. |
Achenes | dark brown, 3-gonous, 1.5–2 mm, glabrous. |
1.5–2 mm. |
2n | = 40. |
= 40. |
Eriogonum rotundifolium |
Eriogonum annuum |
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Phenology | Flowering May–Oct. | Flowering Apr–Nov. |
Habitat | Sandy to gravelly flats and slopes, mixed grassland, saltbush, creosote bush, and mesquite communities, juniper woodlands | Sandy flats, slopes, dunes, and banks, mixed grassland, oak and conifer woodlands |
Elevation | 600-1800 m (2000-5900 ft) | (0-)100-1900(-2300) m ((0-)300-6200(-7500) ft) |
Distribution |
AZ; NM; TX; Mexico (Chihuahua, Coahuila)
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CO; KS; MT; ND; NE; NM; OK; SD; TX; WY; Mexico (Chihuahua)
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Discussion | Eriogonum rotundifolium is the southern counterpart to E. cernuum, being common to abundant and occasionally even weedy. Its overall range, however, is significantly smaller. It occurs in Arizona only in Cochise County, but is found more widely in New Mexico, and is common in the trans-Pecos region of western Texas, with scattered populations in Dimmit, Ector, Foard, and Knox counties outside that region. A sterile Edwin James specimen gathered in 1820 (NY) supposedly was collected near the Rocky Mountains and may be Eriogonum rotundifolium. Also seen at NY is an unattributed, redistributed collection of this species labeled only “Colorado.” Until better documented material from that state is seen, the species is considered not to be a member of the Colorado flora. F. A. Elmore (1943) reported that the round-leaf wild buckwheat was used by the Navajo (Diné) people as an emetic. My own consumption of a few seeds, as a self-experiment, produced no particular urge to vomit. Inasmuch as the treatment was taken after swallowing ants, it is difficult to know whether the ants or the seeds were the emetic. G. M. Hocking (1956) reported that the leaves were used for sore throats and the stems were eaten raw (the latter proving in the same self-experiment not to be particularly tasty, leaving a slightly sour aftertaste). Hocking also reported that the roots were used medicinally but mentioned no specific ailment. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eriogonum annuum is widespread and common to locally abundant or even weedy on the Great Plains of the central United States and extreme north-central Mexico. It was collected in Sherburne County, Minnesota, in 1982, but that population did not persist. The species was recently found as an introduction at Sandy Hook in Monmouth County, New Jersey (Snyder & McArthur s.n., NY), but its fate there remains to be determined. Unfortunately, this weedy species recently has been introduced into northern Arizona as a roadside wild flower. C. L. Perez et al. (1998) have demonstrated that the seed bank can be rich in seeds of this species, but germination rates are low. The Lakota people traditionally used the annual wild buckwheat as an aid in the treatment of sore mouths in children, seemingly in association with teething (D. J. Rogers 1980). Leaves were used to stain buffalo and deer hides by the Kiowa (P. A. Vestal and R. E. Schultes 1939). Vestal (1952) stated that the species was considered a “life medicine” by the Navajo (Diné) people; it was used also for protection against witches. It is likely that E. annuum was obtained by the Navajo through trade, but it might have been grown locally in historic times where the species recently has been reintroduced. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 5, p. 402. | FNA vol. 5. |
Parent taxa | Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Ganysma | Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Micrantha |
Sibling taxa | ||
Synonyms | E. cernuum subsp. glaucescens, E. cernuum subsp. rotundifolium, E. rotundifolium var. angustius | E. annuum subsp. cymosum, E. annuum subsp. hitchcockii |
Name authority | Bentham: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 21. (1856) | Nuttall: Trans. Amer. Philos. Soc., n. s. 5: 164. (1835) |
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