Altered andesite buckwheat in the vicinity of Reno

Altered andesite buckwheat (Eriogonum robustum) of the buckwheat family (Polygonaceae) is a narrowly restricted endemic that occurs in hydrothermally altered andesite areas of the Reno/Sparks area in northwestern Nevada [1-3]. The shown plants grow in Reno's Red Hill area.

Altered andesite buckwheat can be found on dry andesite soil at low elevation including the Red Hill area and slopes of Mt. Peavine and the Geiger Grade [2]. Notice that it also is known under the vernacular name Geiger Grade buckwheat. The plants have leaves that are matted with felty hairs, resulting in a greenish white to silver color.

Altered andesite buckwheat is closely related to Lobb's buckwheat (Eriogonum lobbii), which is found at higher elevation: Whereas Lobb's buckwheat is locally common in alpine and subalpine environments, altered andesite buckwheat is narrowly restricted to cold-desert environments [1].

Andesite is a very finely crystalline extrusive rock of volcanic origin, solidified from molten lava at the Earth's surface. In composition, andesite can be considered an intermediate between basalt and rhyolite: it is composed largely of plagioclase feldspar with smaller amounts of dark-colored mineral [4,5]. Andesite is typically lighter colored than basalt, having a color from dark gray-green to lighter gray, brown or red. The name Red Hill makes a reference to the rust-red color of its hill sides.  

Keywords: botany, biogeography, taxonomy, geology

References and more to explore
[1] K. F. Kuyper, U. Yandell and R. S. Nowak: On the taxonomic status of Eriogonum robustum (Polygonaceae), a rare endemic in Western Nevada. Great Basin Naturalist 1997, 57 (1), pp. 1-10 [ojs.lib.byu.edu/wnan/index.php/wnan/article/viewFile/730/1578].
[2] Laird R. Blackwell: Tahoe Wildflowers • A Month-by-Month Guide to Wildflowers in the Tahoe Basin and Surrounding Areas. A Falcon Guide, Morris Book Publishing, LLC, 2007; page 53.
[3] J. D. Morefield: Current Knowledge and Conservation Status of Eriogonum robustum E. Greene (Polygonaceae), the altered andesite buckwheat. Nevada Natural Heritage Program, Department of Conservation and Natural Resources, 1550 East College Parkway, suite 145, Carson City, NV 89706, December 2000 [heritage.nv.gov/reports/errotext.pdf].
[4] Dictionary of Geology & Mineralogy. Second Edition McGrawHill, New York, 2003.
[5] J. V. Tingley, K. A. Pizarro, C. Ross, B. W. Putkey and L. J. Garside: Geologic and Natural History Tours in the Reno Area. Nevada Bureau of Mines and Geology, University of Nevada, Reno, 2005.