Flora of the Southeastern United States

Trichostema brachiatum Linnaeus. Common name: Glade Blue Curls, False Pennyroyal. Phenology: (Jul-) Aug-Sep (-Oct). Habitat: Shale barrens, outcrops of calcareous or mafic rock, diabase barrens, calcareous dry prairies, disturbed rocky areas. Distribution: Vermont and s. Ontario west to Minnesota and Nebraska, south to c. and w. North Carolina, nc. South Carolina, nw. Georgia, Alabama, Mississippi, Texas, and Arizona.

Origin/Endemic status: Native

Taxonomy Comments: As explained in McClelland & Weakley (2023), the lectotype illustration of T. brachiatum L. (Dillenius 1732) is actually an illustration of T. dichotomum L., meaning that these two names are synonyms. The earliest name for the species previously referred to as T. brachiatum is Isanthus coeruleus Michx. (Michaux 1803). Given that genetic evidence shows that this species should be included in the genus Trichostema (McClelland 2022; McClelland et al. 2023), McClelland & Weakley (2023) made the new combination Trichostema coeruleum K.S. McClell & Weakley. This was opposed by Moore & Poindexter (2024), and the Nomenclature Committee agreed, voting to conserve the usage of T. brachiatum with a new type (Applequist 2026).

Synonymy ⓘ: = Ar, Can, FNA16, GrPl, K4, Mi, Mo3, NcTx, NE, NS, NY, Pa, POWO, Tx, Va, W, Applequist (2026), Lewis (1945); = Isanthus brachiatus (L.) Britton, Sterns, & Poggenb. — C, F, Il, K1, S, Tn, WV; = n/a — RAB, Tat; = Trichostema coeruleum (Michx.) K.S.McClell. & Weakley — McClelland & Weakley (2023) in Weakley et al (2023); > Isanthus brachiatus (L.) Britton, Sterns, & Poggenb. var. brachiatus — G; > Isanthus brachiatus (L.) Britton, Sterns, & Poggenb. var. linearis Fassett — G. Basionym: Trichostema brachiatum L. 1753

Links to other floras: = Trichostema brachiatum - FNA16

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Heliophily ⓘ: 9