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Eriogonum lachnogynum var. colobum
(Clipped wild buckwheat)

[taxon report][distribution map][all photos][line drawing]

Family: Polygonaceae

Scientific Name: Eriogonum lachnogynum Torrey ex Bentham var. colobum Reveal & A. Clifford

Synonyms: None

Vernacular Name: Clipped wild buckwheat

R-E-D Code: 3-2-3

Description: Perennial herb forming a flat mat or cushion-like mound up to 3.5 dm across from an intricately branching caudex; leaves all basal, short-petioled, the blade narrowly elliptic, 4-12 mm long, 1.5-3.5 mm wide, silky tomentose, the margins revolute; inflorescence stems numerous, 2-13 mm long, silky tomentose; inflorescence capitate, not or only slightly exceeding the leaves; involucres 5-lobed, one per flowering stem, 2-3 mm high, 4-5 mm wide; flowers yellow, 3-4.5 mm long; petals villous pubescent on outer surface; ovaries and seeds villous. Flowers late May and June.

Similar Species: Eriogonum lachnogynum is distinguished from other perennial yellow-flowered wild buckwheats in New Mexico by its villous ovaries and seeds. Variety lachnogynum usually has fewer and much longer flowering stems and broader inflorescences than variety colobum and does not form large cushion-like (pulvinate) mats. Variety sarahiae is also a pulvinate plant, but with somewhat longer inflorescence stems that are intermediate between variety colobum and variety lachnogynum.

Distribution: New Mexico, McKinley and Taos counties.

Habitat: Open sandy or gypseous limestone ridges and edges of mesas in piƱon-juniper woodland; about 2,080-2,300 m (6,820-7,540 ft).

Remarks: Presently known only from outcrops of Todilto limestone between Prewitt and Thoreau in McKinley County and limy gravelly soils on the rim of the Rio Grande Gorge in Taos County. These two populations are widely disjunct and may have separately evolved in parallel. The Taos County population is morphologically more variable than the McKinley County population.

Conservation Considerations: Clipped wild buckwheat occurs in very small, widely scattered populations that could be seriously impacted by quarrying or road building activities. Most of the limestone habitat at the holotype locality had previously been mined-out before this variety was discovered. This unpalatable plant is not threatened by livestock grazing.

Important Literature (*Illustration):

Reveal, J.L. and A. Clifford. 2004. A new variety of Eriogonum lachnogynum (Polygonaceae: Eriogonideae). Phytologia 86(3):169-172.

Reveal, J.L. Eriogonum. Pages 218-430, In: Flora of North America Editorial Committee. 2005. Flora of North America, volume 5. Oxford University Press, New York.

Information Compiled By: Robert Sivinski, 2007

Agency Status:
Taxon USFWS State of NM USFS BLM Navajo Nation Natural Heritage NM Global Rank
Eriogonum lachnogynum var. colobumEriogonum lachnogynum var. colobum...S2

Photo credits in header Peniocereus greggii var. greggii © T. Todsen,
Lepidospartum burgessii © M. Howard, Argemone pleiacantha ssp. pinnatisecta © R. Sivinski
©2005 New Mexico Rare Plant Technical Council