Cirsium arvense. (Cnicus Arvensis.) Canada Thistle.
Nat. Ord. — Asteraceae. Sex. Syst. — Syngenesia Aequalia.
Description. — This plant, called in England Cursed Thistle, has a perennial, creeping, very long root, extremely tenacious of life, with a stem three or four feet in hight, having a branching panicle at top. The leaves are alternate, oblong or lanceolate, sessile, smooth, or slightly woolly beneath, sinuate-pinnatifid, and prickly margined. Heads rather small and numerous, imperfectly dioecious ; flowers, rose-purple ; involucre round or ovate, with minute spines, scales close pressed, ovate-lanceolate.
History. — Canada Thistle grows in various sections of the United States, in cultivated fields and pastures, roadsides and waste places, flowering from June to August. It is an extremely troublesome plant to the farmer, requiring his utmost vigilance to extirpate it from his fields. The involucre is the only part of the plant that can be handled with safety. The root is the part employed, which yields its properties to water.
Properties and Uses. — Tonic and astringent. Used principally in diarrhea and dysentery, boiled with milk; some recommend the addition of dried codfish skin to the decoction. Also, used as a local application to some cutaneous diseases, ulcers and leucorrhea.
Off. Prep. — Decoctum Cirsium.