1034 FLORA. 



broad or less, purple or white, sessile or short-peduncled, or some of them rarely 

 solitary and slender peduncled; bracts of the involucre very numerous, linear, the 

 outer prickle-tipped and rigid, the inner thinner and merely acuminate. In waste 

 places, N. B. and N. S., and in ballast about the seaports. Adventive from 

 Europe. Native also of Asia. July-Sept. 



99. MARIANA Hill. 



Annual or biennial, simple or branched, nearly glabrous herbs, with large al- 

 ternate clasping, sinuate-lobed or pinnatifid, white-blotched leaves, and large dis- 

 coid heads of purple tubular flowers, solitary at the end of the stem or branches. 

 Involucre broad, subglobose, its bracts rigid, imbricated in many series, the lower 

 ones fimbriate-spinulose at the broad triangular summit, the middle ones similar 

 but armed with huge spreading or recurved spines, the inner lanceolate, acuminate. 

 Receptacle flat, densely bristly. Corolla-tube slender, the limb expanded and 

 deeply 5-clelt. Filaments monadelphous below, glabrous. Anthers sagittate at 

 the base. Style nearly entire. Achenes obovate-oblong, compressed, glabrous, 

 surmounted by a papillose ring. Pappus-bristles in several series, flattish, barbel- 

 late or scabrous. A monotypic genus of the Mediterranean region. 



1. Mariana Mariana (L.) Hill. Milk Thistle. (I. F. f. 4074.) Stem 

 striate, glabrous or slightly woolly, little branched, 6-12 dm. high. Leaves oblong- 

 lanceolate, prickly, strongly clasping, the lower often 3 dm. long and 15 cm. wide, 

 the upper much smaller, scarcely iobed, acute; heads about 6 cm. broad; spines 

 of the middle involucral bracts often 4 cm. long; pappus bristles white, barbellate. 

 Escaped from gardens near Kingston, Ontario; in ballast about the eastern seaports, 

 and on the Pacific Coast from Br. Col. to southern Cal., where it is naturalized. 

 June-Aug. [Silybum Marianum Gaertn.] 



100. ONOPORDON L. 



Coarse, branching, or rarely acaulescent, tomentose herbs, with stout stems 

 winged by the decurrent bases of the alternate dentate or pinnatifid, prickly leaves, 

 and large discoid heads of purple, violet or white flowers, mostly solitary at the ends 

 of the branches. Involucre nearly globular, its bracts imbricated in many series, 

 all tipped with long spines in our species, the inner narrower than the outer. Re- 

 ceptacle flat, fleshy, honeycombed, not bristly. Corolla-tube slender, the limb 

 expanded and deeply 5-cleft. Filaments pilose. Anthers sagittate at the base. 

 Achenes obovate or oblong, 4-angled or compressed, smooth or corrugated. Pappus- 

 bristles in several series, filiform, barbellate or plumose, united at the base. 

 [Greek, Asses' Thistle, the ancient name.] About 12 species, natives of the Old 

 World. 



i. Onopordon Acanthium L. Cotton Thistle. Scotch Thistle. (I. 

 F. f. 4075.) Biennial, white-tomentose all over; stem usually much branched, 

 leafy, 1-3 m. high. Leaves oblong, lobed and dentate, acute, very spiny, the 

 lower often 3 dm. long; heads 4-5 cm. broad, about 4 cm. high, solitary at the 

 ends of the branches; outer bracts of the involucre ovate or oblong, minutely serru- 

 late, tipped with long, stout, spreading spines; flowers pale purple; achenes slightly 

 corrugated; pappus-bristles brownish, longer than the achene. In waste places, 

 N. S. and Ont. toN. J. and Mich. Nat. from Europe. Native also of Asia. July- 

 Sept. 



101. CENTAUREA L. 



Perennial or annual herbs, with alternate entire, dentate, incised or pinnatifid 

 leaves, and large or middle-sized heads of tubular purple-violet, white or rarely 

 yellow flowers. Involucre ovoid or globose, its bracts imbricated in many series, 

 appressed, fimbrillate, or dentate. Receptacle fiat, densely bristly. Marginal 

 flowers usually neutral and larger than the central ones, which are perfect and fer- 

 tile, or fiower> all perfect and fertile in some species. Corolla tube slender, the 

 limb regnl.tr or oblique, 5-cleft or 5-lobed, the segments sometimes appearing like 

 rays. Anthers sagittate at the base Style-branches short, somewhat connate, ob- 

 tuse. Acnenes oblong or obovoid, compressed or obtusely 4-angled. usually smooth 



and shining, obliquely or laterally attached to the receptacle, surmounted by a disk 

 with an elevated margin. Pappus of several series of bristdes or scales, rarely 



