Cirsium horridulum var. megacanthum

(Nuttall) D. J. Keil

Sida 21: 214. 2004

Common names: Bigspine thistle
Basionyms: Cirsium megacanthum Nuttall Trans. Amer. Philos. Soc., n. s. 7: 421. 1841 (as Circium)
Treatment appears in FNA Volume 19. Treatment on page 115. Mentioned on page 114.
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Illustrator: John Myers
Plants 100–250 cm. Stems glabrous to sparsely tomentose. Leaves: blades oblanceolate or oblong-elliptic, 20–40 cm, shallowly to deeply pinnatifid, main spines 10–30 mm, abaxial faces glabrous or nearly so. Heads 10–20. Involucres 4–5 × 5–8 cm, glabrous. Phyllaries: outer and middle bodies scabridulous or minutely spinulose, marginal spinules usually 1 mm or shorter. Corollas pink to purple. 2n = 32, 34.

Phenology: Flowering spring (Mar–Jun).
Habitat: Meadows, pastures, roadsides, forest openings, low ground, often in damp soil
Elevation: 0–100 m



Ala., Ark., Fla., La., Miss., Okla., Tex.


Variety megacanthum occurs on the coastal plain and lower piedmont from northern Florida to eastern Texas and southeastern Oklahoma. Nuttall described this thistle as “one of the most terribly armed plants in the genus.”



Lower Taxa

No lower taxa listed.

AuthorDavid J. Keil +
Authority(Nuttall) D. J. Keil +
BasionymsCirsium megacanthum +
Common nameBigspine thistle +
DistributionAla. +, Ark. +, Fla. +, La. +, Miss. +, Okla. + and Tex. +
Elevation0–100 m +
HabitatMeadows, pastures, roadsides, forest openings, low ground, often in damp soil +
IllustratorJohn Myers +
PhenologyFlowering spring (Mar–Jun). +
Publication titleSida +
Publication year2004 +
ReferenceNone +
Source xml grained fna xml/V19-20-21/V19 64.xml +
SynonymsCompositae +
Taxon familyAsteraceae +
Taxon nameCirsium horridulum var. megacanthum +
Taxon parentCirsium horridulum +
Taxon rankvariety +
VolumeVolume 19 +