This is a close relative of berlandieri and perhaps should be combined (see also notes under var. zschackei). It has been confused with missouriense and others, partly through misapplication of the name C. paganum Reichenb. (probably a Eurasian form of album). C. buschianum differs from the album group (including missouriense) as follows (FNA 4, W): seeds "honeycomb-pitted" (versus "smooth, indistinctly granulate and/or radially grooved, or with faint reticulate-rugose ridges") and larger on average (mosly 1-2 mm across versus 1-1.5 mm); flowers in glomerules 4-7 mm wide (versus in glomerules 3-4 mm wide or occasionally single); plants typically up to 0.5-1 m tall (versus 2-3 m), generally without purplish coloration (versus often with purplish nodes and stripes on stems); 2n = 36 (versus 54). The berlandieri complex needs deeper analysis in eastern North America. C. bushianum may have originated in midwestern regions, but was apparently spread east to northeastern regions by humans, widely cultivated and selected for its edible seeds, ca. 1000-4000 years ago (Ford 1985, Smith 2006, Halwas & Worley 2019). There are several records from archaeological sites in the Appalachian Cliff Section. Some of these archaeological seeds have been named as a distinct taxon, ssp. jonesanum B. Smith, but any morphological differences from buschianum remain largely obscure. Seed size is similar to modern buschianum, with a mean of ca. 1.3-1.9 mm across; but the seed coat (testa) is reportedly thinner at ca. 11-15 microns versus 43-60 microns (Smith & Funk 1985); see also Crawford et al. (2019). C. buschianum is related to the cultivated South American grain, C. quinoa Willd. In Ky. bushianum is currently verified from only a few colls. on or near banks of the Ohio Rv., and there is a recent (2014) report from cliffs of Indian Hill in EDMO (plants to be cultivated by JC for identification). Based on archaeological work, other weed seeds were also eaten by native people, especially ca. 1000-2000 years ago, and some species were apparently cultivated as well, including Polygonum erectum, Phalaris caroliniana, Hordeum pusillum, Iva annua and Helianthus annuus, with lesser amounts of Ambrosia trifida, Amaranthus sp., Portulaca sp., Galium sp., etc. Such species probably occurred along edges of trails, campsites and villages, and in some cases on fresh alluvium. Corn and beans largely replaced these species in the human diet ca. 1000-1500 years ago.