
Cirsium carolinianum (Walt.) Fern. & Schub.
Carolina Thistle
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G5
State Rank: S3
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): No
SWAP 2025 Species of Greatest Conservation Need (SGCN): No
2025 SGCN Priority Tier: None
Element Occurrences (EOs) in Georgia: 17
Habitat Summary for element in Georgia: Prairies; open mixed pine-oak woods, shortleaf pine-blackjack oak savannas over serpentine
Biennial herb with a hollow, erect stem 20 - 71 inches (50 - 180 cm) tall, smooth or hairy, with few branches and the leaves concentrated on the lower half. Basal leaves are often present at flowering, 3 - 12 inches long and 0.4 - 2 inches wide (8 - 30 cm long and 1 - 5 cm wide), becoming smaller up the stem, alternate; blades are narrowly lance-shaped or elliptic, sharply pointed at the tip and tapering at the base to slender, winged leaf stalks, lobed or unlobed, with numerous irregular, spiny teeth; the upper surface is bright green, the lower surface is covered with a dense layer of white hairs. Stem leaves are similar to the bsal leaves except smaller, widely separated, narrowly oblong, and without leaf stalks. Heads are 1 - 9 per plant, held singly at the tips of long, cobwebby stalks. Each head is 1 - 1.5 inch (2.7 - 4 cm) high (including both involucre and disk flowers), surrounded at the base by a cup-shaped involucre of green bracts; each bract has a prominent white midrib and a long, slender spine at the tip. Numerous dark pink to purple (rarely white), tubular, 5-lobed disk flowers emerge at the top of the involucre bearing dark pink stamens and long pink styles; there are no ray flowers. After fertilization, the flowers are replaced by dry, seed-like fruits bearing long, white or gray pappus bristles that aid in dispersal.
There are 4 or more species of thistle in north Georgia. Carolina Thistle is distinguished by its small heads held on long, cobwebby stalks, narrow leaves less than 2 inches wide, and densely white-hairy lower leaf surfaces. Another rare species, Virginia Thistle (Cirsium virginianum), see below, is very similar to Carolina Thistle but is found only in the Coastal Plain and Fall Line ecoregions.
Musk Thistle or Nodding Thistle (Carduus nutans) is a widespread, highly invasive thistle native to Eurasia that occurs in sunny, disturbed areas such as roadsides and pastures. Its stems have spiny wings, and the leaves are green on both surfaces; at maturity, the flower heads droop or nod at the top of the stem.
LeConte's Thistle (Cirsium lecontei) occurred in two counties in Georgia’s Coastal Plain in wet pine savannas and seepage bogs but has not been seen there for many decades. For more information, see: http://beta.floranorthamerica.org/Cirsium_lecontei
Swamp Thistle (Cirsium muticum) occurs in six Georgia counties in floodplains, live oak hammocks, and wet flatwoods and prairies. http://beta.floranorthamerica.org/Cirsium_muticum
Virginia Thistle (Cirsium virginianum) occurs in two counties in Georgia’s Coastal Plain and Fall Line ecoregions in wet to fairly dry pine savannas and flatwoods, bogs, and ecotones between dry uplands and wet savannas. For more information, see: https://georgiabiodiversity.org/portal/profile?group=plants&es_id=19544
Carolina Thistle occurs in northeast and northwest Georgia in cedar glades, dry to wet prairies, and open pine-oak woodlands and savannas over mafic, ultramafic, or calcareous rocks, and in rights-of-way through these habitats.
Carolina Thistle is a biennial (or short-lived perennial) herb that reproduces exclusively by seed. During its first year, the plant forms a flattened rosette of basal leaves; during its second or third year, a tall stem emerges from the rosette, divides into one or a few branches at the top, and produces 1 - 9 flower heads. The flower heads of thistles are visited by a variety of insect pollinators, including bumblebees, long-horned bees, digger bees, leaf-cutting bees, and many butterfly and moth species. Caterpillars of both butterflies and moths feed on the leaves and stems. Each flower head produces many seeds that are prized by seed-eating birds, including goldfinches, indigo buntings, pine siskins, and juncos, and other small animals. Goldfinches line their nests with the pappus bristles. Their seed-like fruits are tipped with plume-like, pappus bristles and are dispersed by the wind.
Surveys for Carolina Thistle are best conducted during flowering, April–June, though the leaves and fruiting heads are distinctive later in the summer.
Georgia west to Texas, north to Illinois, Ohio, and Virginia. It is rare throughout the eastern portion of its range.
Carolina Thistle is a species of dry, open woodlands, savannas, glades, and prairies. Fire suppression and succession has replaced these open and semi-open habitats with dense forests. Conversion to pine plantations and commercial and residential development has destroyed much of its habitat.
Carolina Thistle is ranked S3 by the Georgia Department of Natural Resources, indicating that it is vulnerable to extirpation in Georgia due to a restricted range, relatively few populations, recent and widespread declines, or other factors. Fifteen populations have been documented in Georgia, most on conservation land, with eight seen since 2000.
Restore woodlands and prairies with frequent, low intensity fires. Protect these habitats from development. Monitor sites for invasion by exotic pest plants. Re-vegetate rights-of-way with native woodland species and manage with ecologically timed mowing.
Cronquist, A. 1980. Vascular Flora of the Southeastern United States: Volume 1, Asteraceae. University of North Carolina Press, Chapel Hill.
GADNR. 2019. Element occurrence records for Cirsium carolinianum. Georgia Department of Natural Resources, Wildlife Resources Division. Social Circle, Georgia.
Helzer, Chris. 2015. Saving pollinators one thistle at a time. Prairie Ecologist, 26 August 2015. The Nature Conservancy, Nebraska. https://prairieecologist.com/2015/08/26/saving-pollinators-one-thistle-at-a-time/
Hilty, J. 2019. Cirsium spp. Illinois Wildflowers. https://www.illinoiswildflowers.info
Keil, DJ. 2006. Species account for Cirsium carolinianum. Flora of North America North of Mexico, vol. 19. http://beta.floranorthamerica.org/Cirsium_carolinianum
NatureServe. 2020. Species account for Cirsium carolinianum. NatureServe Explorer. NatureServe, Arlington, Virginia. http://explorer.natureserve.org/servlet/NatureServe?searchName= Cirsium+carolinianum
Tenaglia, D.E. 2003. Cirsium carolinianum species account, in: Missouri Plants.com. Accessed 18 December 2019. http://www.missouriplants.com/Pinkalt/Cirsium_carolinianum_page.html
Weakley, A.S. 2015. Flora of the southern and mid-Atlantic States. University of North Carolina Herbarium, University of North Carolina, Chapel Hill. http://www.herbarium.unc.edu/flora.htm
Linda G. Chafin
Linda G. Chafin, 18 December 2019: original account