Tiarella austrina

Nesom (2021) splits the broad concept of Tiarella cordifolia recognized by Flora of North America Editorial Committee (2009) into five species. T. stolonifera is a stoloniferous species that is widespread from Michigan to the northeastern U.S. and adjacent Canada and south into Kentucky, Tennessee, and montane Virginia and North Carolina (Nesom 2021). Tiarella cordifolia following Nesom (2021) is a non-stoloniferous species, on the eastern seaboard from Maryland to Georgia. The other three eastern species of Tiarella recognized by Nesom (2021) are restricted to the southeastern U.S: T. austrina, T. wherryi, and T. nautila.

Tiarella austrina is a perennial herb in forests and on rock outcrops in the southern Appalachians of the southeastern United States in southwestern North Carolina, southeastern Tennessee, northwestern South Carolina, and northeastern Georgia with westward disjuncts in southeastern Tennessee and northern Alabama. Delimiting distribution and abundance would benefit from careful review of herbarium specimens and photo-based observations. Monitoring of populations should be conducted to improve our understanding of reproduction, plant abundance, threats, and trends, as well as continuing conservation measures to protect the taxon.

Tiarella austrina occurs in the southern Appalachians in the southeastern United States in the Southern Blue Ridge of southwestern North Carolina (south and west from the Asheville Basin), southeastern Tennessee, northwestern South Carolina, and northeastern Georgia with westward disjuncts in the Cumberland Plateau and Eastern Highland Rim of southeastern Tennessee and northern Alabama (Weakley and the Southeastern Flora Team 2024). Range extent was estimated to be approximately 70,000 square kilometers using herbarium specimens and photo-based observations documented between 1993 and 2024 (iNaturalist 2024, SEINet 2024).

By applying a 1 km separation distance to herbarium specimens and photo-based observations documented between 1993 and 2024, it is estimated that there are between 120 and 300 occurrences rangewide (GBIF 2024, iNaturalist 2024, SEINet 2024). Due to different treatments of this entity as a recent segregate from T. cordifolia, herbarium records and photo-based observations may underrepresent true abundance.

Although threats are not widely documented, this species is potentially threatened by development, logging, recreational activities, invasive species, and other threats in some places, though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species.