Cirsium repandum

Michaux
Fl. Bor.-Amer. 2: 89. 1803.
Common names: Sand-hill or coastal-plain thistle
Endemic
Synonyms: Carduus repandus (Michaux) Persoon
Treatment appears in FNA Volume 19. Treatment on page 113. Mentioned on page 98, 99, 115.

Perennials, 20–80 cm; creeping roots deep-seated, sometimes appearing as taprooted biennials. Stems 1–several, spreading to erect, (usually very leafy in distal 1/2), loosely arachnoid, and villous with jointed, multicellular trichomes; branches 0–few from above middle, ascending. Leaves linear to oblong or oblanceolate, 6–16 × 1–3.5 cm, unlobed to sinuate-dentate or shallowly pinnatifid, main spines 1–4 mm, fine, faces ± green, shaggy-villous with septate trichomes, abaxial loosely arachnoid when young; basal and proximal cauline usually absent at time of flowering; mid and distal nearly uniform in size or gradually reduced, bases clasping; distalmost cauline ± bractlike. Heads 1–5, in corymbiform arrays. Peduncles 0–2 cm. Involucres ovoid or cylindric to campanulate, 2–4 × 1.5–4 cm, loosely arachnoid, ± glabrate. Phyllaries in 6–9 series, imbricate, lanceolate (outer) to linear (inner), abaxial faces with glutinous ridge, outer and middle tightly appressed, bodies scabrous or spinulose, spines erect or weakly ascending, 1–4 mm; apices of inner phyllaries long-acuminate, spineless. Corollas light purple, 33–40 mm, tubes 14–15 mm, throats 12–15 mm, lobes 7–9 mm; style tips 4.5–6 mm. Cypselae light brown, 3.5–4 mm, apical collars yellowish, ca. 0.8 mm; pappi 15–30 mm. 2n = 30.


Phenology: Flowering spring–summer (May–Jul).
Habitat: Sandhills, pine barrens, roadsides
Elevation: 0–150 m

Discussion

Cirsium repandum occurs on the Atlantic coastal plain. R. J. Moore and C. Frankton (1969) suggested that Cirsium repandum originated through ancient hybridization between C. pumilum var. pumilum and C. horridulum. They noted that an artificial hybrid (2n = 32) between C. repandum (2n = 30) and C. horridulum (2n = 34) had a mosaic of features of the parental taxa.

Selected References

None.

Lower Taxa

None.