Silybum Adans.

1 species naturalized Aust.; all states and territories except NT

*Silybum marianum (L.) Gaertn.

Erect, glabrous biennial up to 3 m high. Leaves basal and cauline, glossy, mottled with white veins, ± pinnatifid, with spiny margins; the uppermost stem-clasping. Heads solitary on leafy peduncles. Involucre subglobular, 4 cm diam.; bracts broad, rigid, with a rounded appendage terminating in a spine. Florets all tubular, purple. Cypselas black, glossy, glabrous, 5–6 mm long. Pappus of numerous simple unequal hairs, 12–20 mm long. Widespread. Weed of cultivation, pastures and waste places especially around stockyards. Poisonous to stock. Introd. from the Mediterranean. Fl. chiefly spring. Variegated Thistle