Sarcobatus Nees., a genus of North American halophytic shrubs, consists of 2 species: S. vermiculatus (Hook.) Torr. (n = 18, 36), which is widespread in North America, and S. baileyi Cov. (n = 54), endemic to Nevada. Within S. vermiculatus, populations of n = 36 are widely distributed, whereas populations of n = 18 are found only in the Sonoran Desert, northern California, and northwestern Great Plains, locations at the periphery of the species range. Although the chromosome number of n = 18 is apparently tetraploid, failure to form an n = 27 race intermediate to those of n = 18 and n = 36 suggests than n = 18 S. vermiculatus is of significant age and that it behaves chromosomally as a diploid. Sarcobatus has a long fossil pollen record and endured Pleistocene climatic extremes with little range displacement.
Sanderson, Stewart C.; Stutz, Howard C.; Stutz, Mildred; and Roos, Richard C.
"Chromosome races in Sarcobatus (Sarcobataceae, Caryophyllales),"
Great Basin Naturalist: Vol. 59
, Article 1.
Available at: http://scholarsarchive.byu.edu/gbn/vol59/iss4/1