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..
An annual herb, with alternate pinnatifid or sinuate-dentate leaves, the lobes or teeth spiny, and large sessile heads of yellow tubular flowers, solitary at the ends of the branches, subtended by the upper leaves. Bracts of the involucre imbricated in several series, the outer ovate, the inner lanceolate, tipped by long pinnately branched spines. Receptacle flat, bristly. Achenes terete, striate, laterally attached, the horny margin 10-toothed at the summit; pappus of 2 series of awns, the inner fimbriate, the outer longer, naked; anther-appendages elongated, united to their tips. [Latin name of Safflower, early applied to thistles.]
A monotypic genus of the Old World.
Cnicus benedictus L. Sp. Pl. 826. 1753. Centaurea benedic a L. Sp. Pl. Ed. 2, 1296. 1763.
Hirsute or pubescent, much branched, seldom over 2 1/2º high. Leaves oblong-lanceolate in outline, rather thin, reticulate-veined, 3'-6' long, the upper clasping, the basal and lower ones narrowed at the base and petioled; heads about 2' broad, subtended by several large lanceolate to ovate-lanceolate leaves; bristles of the receptacle soft, long; outer awns of the pappus alternating with the inner.
In waste places, Nova Scotia and New Brunswick to Maryland, Pennsylvania, Alabama and Michigan, and on the Pacific Coast. Adventive from southern Europe. Holy- or bitter thistle. Sweet-sultan. St. Benedict's-thistle. May-Aug.
Echinops sphaerocephalus L., a tall spinose plant, with large clusters of 1-flowered involucres, the flowers white or bluish, occasionally escapes from cultivation into waste grounds. It is native of Europe.