Eriogonum leptocladon |
Eriogonum exaltatum |
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fine branch wild buckwheat, sand buckwheat, sand wild buckwheat |
ladder buckwheat, ladder wild buckwheat |
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Habit | Shrubs, erect to spreading, not scapose, (2–)3–10(–12) × 5–15(–20) dm, white-tomentose to floccose, or green and nearly glabrous. | Herbs, erect, annual, (0.5–)3–6(–10) dm, glabrous, glaucous, grayish. | ||||||||
Stems | spreading, often without persistent leaf bases, up to 1/2 height of plant; caudex stems absent or spreading in moving sand; aerial flowering stems spreading, slender, solid, not fistulose, 0.3–1 dm, white-tomentose, floccose to glabrate or glabrous. |
caudex absent; aerial flowering stems erect, solid, not fistulose, (0.5–)1–2 dm, glabrous. |
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Leaves | cauline, 1 per node; petiole 0.2–0.5 cm, tomentose to floccose; blade linear-lanceolate to linear-oblanceolate to narrowly oblong, or lanceolate to narrowly elliptic, 1.5–4 × 0.2–0.8(–1.2) cm, densely white-tomentose abaxially, less so and greenish adaxially, margins plane, infrequently revolute. |
basal; petiole 1–10 cm, tomentose; blade sub-cordate to orbiculate, (1.5–)2–5(–8) × (1.5–)2–5(–8) cm, densely white-tomentose abaxially, floccose to subglabrous and green adaxially, margins often wavy. |
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Inflorescences | cymose, open, 5–40 × 10–50 cm; branches dichtomous proximally, often with involucres racemosely arranged proximally, tomentose to floccose or glabrate, occasionally glabrous; bracts 3, scalelike, linear to triangular, 1–3(–6) mm. |
cymose, spreading when immature, quickly becoming narrowly erect and strict with whiplike branches, (5–)10–50(–80) × 10–50 cm; branches glabrous, glaucous; bracts 3, scalelike, 1–1.5(–2) × 0.4–1 mm. |
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Peduncles | absent. |
absent or erect, straight, slender, 0.1–0.2 cm, glabrous. |
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Involucres | 1 per node, turbinate to turbinate-campanulate, 1.5–3 × 1–2 mm, tomentose to floccose or glabrous; teeth 5, erect, 0.4–0.7 mm. |
turbinate, 2–2.5(–3) × 1.5–2.5 mm, glabrous; teeth 5, erect, 0.5–1.5 mm. |
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Flowers | (2–)2.5–3.5 mm; perianth white or pale yellow to yellow, glabrous; tepals connate proximal 1/4–1/3, essentially monomorphic, oblong to broadly obovate; stamens slightly exserted, 2–4 mm; filaments sparsely pilose proximally. |
1.5–2 mm; perianth white with green or reddish midribs, becoming pinkish, glabrous; tepals dimorphic, those of outer whorl oblong, those of inner whorl lanceolate; stamens exserted, 1.5–2.5 mm; filaments pilose proximally. |
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Achenes | light brown, 2.5–3.5 mm, glabrous except for minutely papillate beak. |
dark brown to blackish, 3-gonous, 2–2.5 mm, glabrous. |
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2n | = 40. |
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Eriogonum leptocladon |
Eriogonum exaltatum |
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Phenology | Flowering May–Oct. | |||||||||
Habitat | Sandy to gravelly flats and slopes, saltbush, creosote bush, greasewood, blackbrush, and mesquite communities, rarely in pinyon-juniper woodlands | |||||||||
Elevation | 500-1400 m (1600-4600 ft) | |||||||||
Distribution |
AZ; CO; NM; UT
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AZ; CA; NV; UT |
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Discussion | Varieties 3 (3 in the flora). Eriogonum leptocladon is localized on moving sands on the Colorado Plateau. It is not unusual, therefore, for portions of the shrub to be buried in sand, especially the main, woody trunk from which the flowering stems arise. In the Four Corners area three species share portions of overlapping ranges, and herbarium material from there can be difficult to separate. In northwestern New Mexico, var. ramosissimum approaches E. effusum, and in eastern San Juan County the two can be distinguished only by the open, spreading inflorescence branching pattern of var. ramosissimum as compared to the densely branched, compact inflorescence of E. effusum. In the field, the former is confined to sandy areas whereas the latter is typically on heavier, usually clayey soils. In south-central Utah, var. ramosissimum approaches E. nummulare. There, both are found on moving sands, and only the degree of stoutness of the branches can be used to differentiate them when cauline leaves are absent. For the most part, the inflorescence branches of E. nummulare are more rigid and stouter than those of var. ramosissimum, which tend to be flexible and slender. When leaves are present, those of the former are broader and more apically rounded compared to those of the latter. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Eriogonum insigne has been a troublesome taxon. The type, collected by E. Palmer in 1876, is a curious specimen from near Paragonah in Iron County, Utah. That expression has not been recollected and, after another frustrating review of the type material, it is now referred to E. deflexum, along with other odd specimens from southern Nevada and California that have always been difficult to assign. As a result, the tall, upright plants with long, whiplike branches of northwestern Arizona (Mohave County), southern Nevada (northeastern Clark and southern Lincoln counties), and southwestern Utah (southwestern Washington County), are now recognized under the name E. exaltatum. Some specimens remain problematic. Immature plants of E. exaltatum (Goodding 2302, GH, MIN, MO, NY, RM, UC) resemble E. bifurcatum. Specimens from Eureka Valley (DeDecker 4741, NY) and western Pahrump Valley (Abrams 14248, DS, GH, NY) in Inyo County, California, appear to belong to E. exaltatum. Like Eriogonum exaltatum, some populations of E. deflexum var. deflexum have nearly erect involucres. The plants from the Buried Hills (Nye and Clark counties, Nevada) are particularly odd. Single plants from a few collections in Kane County, Utah, have sessile, seemingly erect involucres in the forks of inflorescence branches. None of these plants has the characteristic long, whiplike branches of E. exaltatum, and they are not included in E. deflexum var. deflexum. The type of E. deflexum var. rectum from San Bernardino County, California (Reveal & Broome 6385, CAS, NY, US, etc.), has individual specimens with both deflexed and somewhat erect involucres, along with whiplike branches. Collections from Imperial and San Diego counties, previously associated with what is here termed E. exaltatum, are now considered specimens of E. deflexum. Clearly, more work is required to understand these species fully. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 5, p. 249. | FNA vol. 5, p. 397. | ||||||||
Parent taxa | Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Eucycla | Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Ganysma | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | E. effusum subsp. leptocladon | |||||||||
Name authority | Torrey & A. Gray: in War Department [U.S.], Pacif. Railr. Rep. 2(1): 129. (1857) | M. E. Jones: Contr. W. Bot. 15: 61. (1929) | ||||||||
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