Cirsium virginianum

Cirsium virginianum is a wide-ranging biennial or perennial herb in a variety of wetland habitats that is endemic to the eastern United States from from southern New Jersey south to northeastern Florida on the Atlantic Coastal Plain. True abundance may be underestimated due to taxonomic challenges and avoidance of thistle collection, and there are at least 54 occurrences rangewide, several of which are protected on national and state owned lands. This species faces numerous threats from habitat loss and degradation, including development, silviculture and agriculture, hydrogical alteration, recreational activities, nonnative insects, and invasive species. Research is needed to better understand the species' life history and ecology. 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.

Cirsium virginianum occurs in the eastern United States from from southern New Jersey south to northeastern Florida on the Atlantic Coastal Plain (FNA 2006). It has been documented from the following counties by state: New Jersey (Atlantic, Burlington, Cape May, and Ocean Counties), Delaware (Sussex County), none in Maryland, eight in Virginia, 26 in North Carolina, thirteen in South Carolina, seven in Georgia, and Florida (Clay and Duval Counties). Range extent was estimated to be 272,764 square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1993 and 2024 (GBIF 2024, iNaturalist 2024, NatureServe 2024, SEINet 2024).

By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1993 and 2024, it is estimated that there are 54 occurrences rangewide (GBIF 2024, iNaturalist 2024, NatureServe 2024, SEINet 2024). Due to taxonomic challenges of this entity (some floras do not consider it distinct) and potential avoidance of collection, herbarium records may underrepresent true abundance. Field surveys of potentially historic occurrences are needed to determine if plants are extant.

Although threats are not widely documented, this species is threatened by habitat loss from development (suburban sprawl and industrial development), conversion to pine plantations and subsequent logging activities, draining and clearing for agriculture, and draining for mosquito control; the species is also threatened by habitat degradation from rights-of-way maintenance, recreational activities (especially off-road vehicles), succession and fire suppression, sea level rise and increasing salination of sea level fens, trash deposition, and invasive species (such as common reed - Phragmites australis), though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species (Chafin 2019, Dodds 2023, NatureServe 2024). Rights-of-way maintenance may benefit this species by maintaining and open habitat and reducing competition if mowing occurs after seeds have matured. Additional threats may arise from members of this genus being treated as noxious weeds with control efforts through herbicides and exotic insects that were introduced to control nonnative thistles (Dodds 2023). While reduced seed production, declining population growth, and even the possibility of extinction for one species have been reported, the impact of nonnative insects on this species are unknown (see citations in Dodds 2023).