Taxonomy

Onopordum acanthium L., Sp. pl. 2:827. 1753

Common synonyms

Acanos spina Scop.; Acanthium onopordon Gueldenst.; Carduus acanthium (L.) Baill.; Onopordon acanthium L.; Onopordum acanthium var. acanthium

Common name

Scotch Thistle, Scott Cotton Thistle

Description

Propagule or dispersal unit is the fruit with pappus. Fertile part 3.5-5.5 mm long, 2-3 mm wide, in side view widest in upper part (obovoid), +/- straight, the upper (apical) end narrowing, in cross-section flattened, rarely angular (prismatic), basal scar (carpopodium) pronounced and well-differentiated, off to the side (oblique) or at least asymmetric, beak (=thinner sterile stalk between seed and pappus) absent, wings absent, fruit surface light brown or straw or dark brown, wrinkled, with no hairs (glabrous), thickened margin absent, longitudinal ribs present, 4-10, their surfaces smooth, with no hairs (glabrous).

Pappus type bristles / hairs, pappus elements all +/- similar, up to (2.5-)5-11 mm long, in several rows, pappus elements numerous, falling off as a whole, the individual bristles rough / serrated (barbellate), +/- equal width along length or clearly wider at base, yellowish.

Ecology

Large biennial herb, seeds wind-dispersed. Temperate regions. Weed in particular of pastures, but also croplands, various disturbed areas and wastelands, and along roads.