Cirsium horridulum Michx. var. horridulum

Horrid Thistle; Yellow Thistle

Herb

Biennial

Vascular

Horrid Thistle is a native herbaceous biennial in the Sunflower family (Asteraceae). It found throughout Alabama. Horrid Thistle grows in dry to moist, open areas such as pastures, roadsides, lawns, and open, disturbed woodlands. It is a biennial with a stout taproot. During the first year of growth the plant forms a basal rosette of leaves. During the second spring, an erect flowering stalk 1-5 feet in height emerges. The stem is hollow, usually unbranched, densely tomentose, with alternate leaves. Stem leaves are sessile to auriculate clasping, oblanceolate or oblong-elliptic in outline, loosely tomentose on the lower surface, with spiny dentate margins. The spines are up to 1/3 of an inch in length. Basal leaves are similar but larger and with spiny winged petioles. Leaves are 5-12 inches in length. Flowers are produced in heads. The heads are solitary or in corymbs. Each head is subtended by an involucre-like ring of densely tomentose, spiny-margined bracts. Corollas are yellow to purple-red in color. The fruit is an achene with a crown of plumose bristles.—A. Diamond

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Native

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