This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
(the ancient Latin name of these plants). Compositae. Thistle. Spiny-leaved annual, biennial or perennial herbs, sometimes grown in borders and rock-gardens for the interesting habit and the heads of purple or white flowers.
Fig. 795. Leaf of Canada thistle. - Carduus arvensis or Cirsium arvense. (X 1/3)
Carduus is sometimes united with Cirsium, but is here kept distinct, being separated chiefly by non-plumose or only indistinctly serrate pappus-bristles (see Cirsium). The common weedy thistles are referred either to Carduus or Cirsium, depending on the definition of the genus. Fig. 795 shows the spiny leaf of one of these. Under the restricted use of the name, Carduus comprises about 80 species, from the Canary Isls. to Japan. For C. benedictus, see Cnicus.
Linn. A much-branched perennial about 18-24 in. high: leaves bright green, pinnately parted, the nerves very prominent beneath, spinose margined: the solitary heads long-peduncled, the fls purple and showy. S. Eu. - Scarcely known in Amer.
C. Marianus, Hort., is a Silybum, and C. tauricum, Hort., is a Cirsium. Both are advertised in England, but are unknown in
Amer. N. Taylor.†