Opuntia cespitosa

Rafinesque, Bulletin Botanique 2: 216, 1830

Herbarium (submitted as O. humifusa); Herbarium (submitted as O. humifusa); Herbarium; Herbarium; Herbarium (submitted as O. humifusa); Herbarium; Herbarium; Herbarium; Herbarium

Opuntia cespitosa is a taxon included in the broadly defined O. humifusa group (O. humifusa s.l.). O. cespitosa resembles O. humifusa and has long been overlooked by botanists because it was considered synonymous with O. humifusa. The cladodes may appear glaucous-gray. Unlike O. humifusa, O. cespitosa has yellow flowers with red centers. O. cespitosa is found in multiple eastern and midwestern states including AL, AR, CT, IL, IN, KY, MA, MD, MI, MO, MS, NY, OH, TN, TX, VA and WV. It even occurs in far southern Ontario, Canada. It is not generally a plant of the Southeast. See the original description. O. cespitosa is tetraploid.

Various relevant scientific papers have reported on this taxon that is within the O. humifusa group (clade): Majure, 2014; Majure et al., 2012; Majure and Ervin, 2007. The Flora of the Southern and Mid-Atlantic States (2015) reports:

Vegetatively, it is most similar to O. mesacantha ssp. mesacantha, from which this allopolyploid may be partially derived, although floral features are quite different, and O. cespitosa does not have the strongly retrorsely-barbed spines common in O. mesacantha. This species also can be confused with certain forms of O. macrorhiza, another putative parent of O. cespitosa; both species have yellow inner tepals basally tinged red adaxially.