Eriogonum rotundifolium |
Eriogonum effusum |
|
---|---|---|
round-leaf wild buckwheat, roundleaf buckwheat |
spreading buckwheat, spreading wild buckwheat |
|
Habit | Herbs, spreading, annual, 0.5–4 dm, glabrous and often glaucous, greenish to grayish. | Shrubs, spreading, not scapose, (1.5–)2–5(–7) × 5–15 dm, grayish- to reddish-brown-tomentose to floccose and gray or, rarely, thinly floccose and greenish. |
Stems | caudex absent; aerial flowering stems erect, solid, not fistulose, 0.1–0.5(–0.7) dm, glabrous. |
spreading to erect, typically without persistent leaf bases, up to 1/2 height of plant; caudex stems absent; aerial flowering stems erect to spreading, slender, solid, not fistulose, 0.3–0.8 dm, floccose or glabrous. |
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. |
cauline, 1 per node; petiole 0.2–0.7 cm, tomentose to floccose; blade oblanceolate to oblong or obovate, (1–)1.5–3 × (0.2–)0.3–0.7 cm, densely white-tomentose abaxially, white-floccose to glabrate or green and glabrous adaxially, margins plane. |
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. |
cymose, 10–30(–40) × 10–40 cm; branches dichotomous, white-floccose to glabrate or subglabrous; bracts 3, scalelike, triangular, 0.5–2(–5) mm. |
Peduncles | erect, straight, stoutish, 0.3–1.5 cm, glabrous. |
absent or mostly erect, slender, 0.3–2.5 cm, floccose. |
Involucres | turbinate to campanulate, 1–2 × 1.5–2.5 mm, glabrous; teeth 5, erect, 0.4–0.8 mm. |
1 per node, turbinate, 1.5–2.5(–3) × 1–2 mm, tomentose to floccose; teeth 5, erect, 0.3–0.6 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. |
2–4 mm; perianth yellow, glabrous; tepals connate proximal 1/4, essentially monomorphic, elliptic to obovate; stamens mostly exserted, 2–4.5 mm; filaments sparsely pilose proximally. |
Achenes | dark brown, 3-gonous, 1.5–2 mm, glabrous. |
brown, 2–2.5 mm, glabrous. |
2n | = 40. |
|
Eriogonum rotundifolium |
Eriogonum effusum |
|
Phenology | Flowering May–Oct. | Flowering Jun–Sep. |
Habitat | Sandy to gravelly flats and slopes, mixed grassland, saltbush, creosote bush, and mesquite communities, juniper woodlands | Sandy to rocky slopes and flats, mixed grassland and sagebrush communities, juniper and montane conifer woodlands |
Elevation | 600-1800 m (2000-5900 ft) | 1200-2500 m (3900-8200 ft) |
Distribution |
AZ; NM; TX; Mexico (Chihuahua, Coahuila)
|
CO; MT; NE; NM; SD; WY
|
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 effusum is rather common on the northern Great Plains and along the eastern slope of the Rocky Mountains in central and eastern Colorado, southeastern Montana, western Nebraska, northern New Mexico, southwestern South Dakota, and southeastern Wyoming. Some specimens from Chaffee County, Colorado, are thinly floccose and greenish (Atwood & Welsh 29689, BRY) and thus similar to E. leptocladon. A collection from Pyramid Lake, Washoe County, Nevada (Frandsen & Brown 182, NESH) is clearly mislabeled. A roadside collection of E. effusum gathered near Little America, Sweetwater County, Wyoming, in 1961 (G. Mason 4025, ASU) was an introduction that has not persisted. The spreading wild buckwheat is occasionally merged with Eriogonum microthecum even though the two are morphologically distinct and their ranges do not overlap. Plants in New Mexico are sometimes difficult to distinguish from the related E. leptocladon var. ramosissimum. The species is the food plant for the Rita dotted-blue butterfly (Euphilotes rita). A hybrid between Eriogonum effusum and E. pauciflorum has been named E. ×nebraskense Rydberg [E. multiceps Nees subsp. nebraskense (Rydberg) S. Stokes; E. pauciflorum Pursh var. nebraskense (Rydberg) Reveal]. The hybrid is known from Weld County, Colorado; Cheyenne and Kimball counties, Nebraska; and Converse and Platte counties, Wyoming. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 5, p. 402. | FNA vol. 5, p. 248. |
Parent taxa | Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Ganysma | Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Eucycla |
Sibling taxa | ||
Synonyms | E. cernuum subsp. glaucescens, E. cernuum subsp. rotundifolium, E. rotundifolium var. angustius | E. microthecum var. effusum |
Name authority | Bentham: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 14: 21. (1856) | Nuttall: Proc. Acad. Nat. Sci. Philadelphia 4: 15. (1848) |
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