Rudbeckia bicolor Nuttall. Hab: Sandstone glades, other dry soils.
Origin/Endemic status: Endemic
Taxonomy Comments: There is a major discrepancy in two conflicting names, Rudbeckia bicolor Nutt. and Rudbeckia hirta L. var. pulcherrima Farr., and to which material these names appropriately refer. Nuttall's type for Rudbeckia bicolor from "R. River", in Arkansas, was published in 1834 (Journ. Acad. Philad. 7:81), which predated Farwell's published name of Rudbeckia hirta var. pulcherrima (Michigan Acad. Sci. 6:209. 1904). Farwell simply describes R. hirta var. pulcherrima as a “form that differs from the species only in having a part of the upper surface of the ray, or even the whole upper face, brown-purple.” Nuttall describes R. bicolor as (translated): annual, pilose, scabrous, stem unicolored; leaves oblong, sessile, rarely subserrate or obtuse, with the lower subovate and petiolate; and with short rays of color (the lower half of rays brown colored). He also states it is somewhat related to R. serotina (another apparent synonym of var. pulcherrima), but he elaborates, “…the flower is entirely different, the leaves all nearly oblong and softly hairy…In Arkansas and near to Red River.” Some authors choose to synonymize R. bicolor into R. hirta var. pulcherrima (GBIF 2022, ITIS 2022, Keener et al. 2022, Urbatsch and Cox in FNA vol. 21 (2006c)). If the two are not recognized as distinct, then one name needs to be prioritized, which would depend on its recognition at varietal or species rank. Both taxa are also buried deeply into other synonyms (e.g. R. serotina, R. sericea, R. lanceolata, R. longipes, R. hirta var. corymbifera, R. hirta var. serotina). R. hirta var. pulcherrima is apparently a widespread weedier species of disturbed areas and R. bicolor may be more restricted to sandstone glades and similar habitats in a handful of states in the southeast and lower midwest. Farwell’s short description lists R. hirta var. pulcherrima from Detroit, Michigan, which may have not included analysis of southern material (i.e. “bicolor”). The R. hirta and R. fulgida complexes are both widespread and highly variable, and unsurprisingly accompany a complicated history of synonymy and taxon recognition. Haines (2011) recognizes R. bicolor as distinct from R. hirta as annual plants lacking basal tufts of leaves with cauline leaves of consistent size proximally and distally and all leaves being sessile or subsessile (vs. R. hirta as biennial or short-lived perennials with basal tufts of leaves and cauline leaves decreasing in size distally, with lower leaves borne on petioles). However, Haines (2011) lists both R. bicolor and R. hirta var. pulcherrima as adventive species in New England, with the former only being reported from MA. Numerous specimens from the apparent native range of both taxa (AL, AR, etc…) show tremendous overlap in cauline leaf shape and size (Kral 53236, Kral 58158, Parker 853, Spaulding 11911, Diamond 13617), which appear to have upper cauline leaves broadly oblanceolate to distinctly linear-lanceolate, although few specimens contain persistent basal tufts of leaves which complicates distinctions listed in Haines (2011). We choose to currently recognize both R. bicolor and R. hirta var. pulcherrima as distinct pending further research that determines to what extent the two taxa are distinct morphologically, geographically, and ecologically.
Synonymy: = F, NE, S; < Rudbeckia hirta L. var. hirta – C, K3, K4; < Rudbeckia hirta L. var. pulcherrima Farw. – FNA21