This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Herbs resembling Cirsium in habit, usually annual or biennial, the leaves decurrent on the stem and branches as spiny wings, the heads often nodding. Involucre ovoid to globose, many-flowered, its bracts narrow, in many series. Receptacle copiously bristly, flat or convex. Corolla-tube slender, the limb deeply 5-cleft. Filaments papillose-pubescent. Anthers sagittate at the base and with slender auricular appendages. Style-branches obtuse. Achenes mostly obovoid, sometimes angled or ribbed, glabrous. Pappus of many naked or merely roughened bristles. [Ancient Latin name of these plants.]
About 80 species, natives of the Old World. Type species: Carduus nutans L. Heads solitary at end of stem or branches, nodding.
1. C. nutans.
Heads usually several, crowded at ends of winged branches.
2. C. crispus.
Carduus nutans L. Sp. Pl. 821. 1753.
Biennial, branched, sparingly tomentose, 2°-3° high. Leaves lanceolate in outline, deeply pinnatifid, acuminate, 3'-6' long, the lobes triangular, very prickly; heads long-peduncled, solitary at the end of the stem or branches, 1 1/2'-2 1/2' broad, nodding, purple, rarely white, fragrant; involucre hemispheric, its bracts in many series, lanceolate, long-acuminate, the prominent mid-nerve prolonged into a prickle, or the inner nerveless and awned; pappus bristles 10"-1' long, white, very minutely barbed.
In waste places, District of Columbia, Pennsylvania and New Jersey to New Brunswick, and in ballast about the seaports. Naturalized or adventive from Europe. Native also of Asia. Bank- or buck-thistle. Queen Ann's-thistle. July-Oct.
Fig. 4653. Carduus Crispus L. Sp. Pl. 821. 1753
Biennial, somewhat tomentose; stem much branched, densely prickly, 2°-4° high. Leaves lanceolate in outline, with undulate and ciliate-spiny margins, all sinuate-pinnatifid into broad, 3-lobed, toothed segments, the teeth prickle-pointed; heads several, usually crowded at the ends of the winged branches, 1' broad or less, purple or white, sessile or short-peduncled, or some of them rarely solitary and slender-peduncled; involucre ovoid, its bracts very numerous, linear, the outer prickle-tipped and rigid, the inner thinner and merely acuminate.
In fields and waste places, New Brunswick, Quebec, Nova Scotia and Pennsylvania, and in ballast about the seaports. Adventive from Europe. Native also of Asia. July-Sept.
Carduus acanthoides L., which resembles this species, but has larger hemispheric involucres, their outer bracts not rigid, has been collected in ballast on waste grounds about Atlantic seaports, and several other species of Carduus have been found in ballast deposits.