Cirsium horridulum var. horridulum

Common names: Horrid thistle
Basionym: Carduus spinosissimus Walter 1788
Synonyms: Carduus horridulum var. elliottii
Treatment appears in FNA Volume 19. Treatment on page 115. Mentioned on page 114, 116.

Plants 15–180 cm. Stems densely tomentose. Leaves: blades oblanceolate or oblong-elliptic, 10–30 cm, shallowly to deeply pinnatifid, main spines mostly 5–10 mm, abaxial faces loosely tomentose. Heads 1–10. Involucres 4–5 × 5–7 cm, ± densely tomentose. Phyllaries: outer and middle bodies scabridulous or minutely spinulose, marginal spinules usually 1 mm or shorter. Corollas yellow or crimson to red-purple. 2n = 32, 34.

Phenology: Flowering winter–spring (Apr–Jun).
Habitat: Fields, meadows, pinelands, roadsides, often weedy, often in damp soil
Elevation: 0–300 m



Ala., Conn., Del., Fla., Ga., La., Maine, Md., Mass., Miss., N.H., N.J., N.Y., N.C., Pa., R.I., S.C., Tenn., Tex., Va.


Variety horridulum occurs on the Atlantic and Gulf coastal plains fom southern Maine to Florida and west to eastern Texas and into the piedmont in much of the southeastern United States. Artificial hybrids have been produced between var. horridulum and Cirsium repandum (R. J. Moore and C. Frankton 1969), and natural hybrids with C. pumilum var. pumilum have been reported.

Selected References


Lower Taxa

David J. Keil +
Michaux +
Carduus spinosissimus +
Horrid thistle +
Ala. +, Conn. +, Del. +, Fla. +, Ga. +, La. +, Maine +, Md. +, Mass. +, Miss. +, N.H. +, N.J. +, N.Y. +, N.C. +, Pa. +, R.I. +, S.C. +, Tenn. +, Tex. +  and Va. +
0–300 m +
Fields, meadows, pinelands, roadsides, often weedy, often in damp soil +
Flowering winter–spring (Apr–Jun). +
Fl. Bor.-Amer. +
Carduus horridulum var. elliottii +
Cirsium horridulum var. horridulum +
Cirsium horridulum +
variety +