Parnassia grandifolia DC.

Parnassia grandifolia DC. View in CoL [ Parnassiaceae ] Large-Leaf Grass-of-Parnassus

Large-Leaf Grass-of-Parnassus was known from asingle, isolated locality in Bibb County where asmall population (ca. 200 individuals) grows in close association with Ketona Dolomite along a small tributary. This rare S1 ( ALNHP 2023; Keener et al. 2023) taxon has been collected from this site in Bibb County (by many botanists) since its discovery there in the late 1970s [Bibb Co., 30 Oct 1977, Sessler 1938 (AUA)]. The only additional known collection for Alabama was in Choctaw County [Choctaw Co., 12 Oct 1951, Harper 4191 (UNA)] which, despite repeated searches, has not been relocated. The newly reported Conecuh County population, with thousands of individuals, represents the first new county discovery and the largest known population for the species in Alabama in almost 50 years. Compared to the Bibb County population, the plants at this Conecuh County site bear a close resemblance to those of the disjunct Apalachicola Florida region, possibly representing a genetic bridge between Apalachicola and the Appalachian Foothills populations (A. Floden pers. comm. 2020).

Parnassia grandifolia (G3) is uncommon across its southeastern range, primarily growing in the Appalachian and Ozark Highlands, most often in either calcareous or ultramafic settings, and rarely in Coastal Plain fens and seeps (Kartesz/BONAP 2024; Weakley & Southeastern Flora Team 2023). The global rarity of this species, as well as its peculiar distribution, makes this Conecuh County location remarkable in the Alabama flora.

Voucher Specimen: ALABAMA. Conecuh Co.: Large population (ca.10,000 stems) growing on nearly vertical calcareous clay north bank of the Sepulga River with moderate seepage; plants almost rhizomatous in habit, with dark green ovary, emarginate petal margins, and bright, orange pollen; growing with Pelazoneuron ovatum (R.P.St.John) A.R.Sm.& S.E. Fawc. and Adiantum capillus-veneris L., 17 Nov 2020, Noah D. Yawn 101 (ALNHS 6984).