COMPOSITAE (composite FAMILY) 859 



chiefly plane and uncut, or the lowest slightly pinnatifid. — Local, Que., N. E., 

 and N. Y. (Nat. from Eu.) 



•^ -i- At least the lower leaves strongly decurrent. 



14. C. PALusTRE (L.) Scop. Tall, not stoloniferous ; stem armed throughout 

 hii the prickly decurrent icings which extend down from the very long linear or 

 linear-lanceolate more or less pinnatifid spinose-ciliate leaves ; heads re.sembling 

 those of no. 13, but in denser gloraerulate clusters, hermaphrodite. — Thoroughly 

 ]iaturalized in woods. East Andover, N. H. ((r. W. Holt). (Nat. from Eu.) 



15. C. c\num (L.) Bieb. Boots fusiform ; lower leaves very long, lanceo- 

 late, toothed or slightly pinnatifid, green on both sides, their bases decurrent as 

 ciliate icings along the stem; upper leaves sessile; heads comparatively large, 

 hemispherical, on long peduncles. — Established at Kendal Green, Mass. {Miss 

 Parsons). (Adv. from Eu.) 



84. 0N0p6rDUM [Vaill.] L. Cotton or Scotch Thistle 



Receptacle deeply honey-combed, not setose. Pappus not plumose. Other- 

 wise as Cirsinm. — Coarse branching annuals or biennials, with the stems 

 winged by the decurrent bases of the lobed and toothed somewhat prickly leaves. 

 Heads large ; flowers purple. (Latinized from the ancient Greek name of the 

 plant. ) 



1. 0. AcANTHiuM L. Stem (1-8 ra. high) and leaves cotton- woolly ; scales 

 iinear-awl-shaped. — Roadsides and waste places, N. B. and N. S. to Out., s. to 

 N. J. and Mich., rather rare. July-Sept. (Nat. from Eu.) 



85. SILYBUM [Vaill.] Adans. Milk Thistle 



Heads many-flowered ; flowers all alike, tubular, perfect, fertile, involucre 

 large, depressed-globose ; the bracts large, prickly, the broadly ovate base 

 gTadually or rather abruptly contracted to a straightish rigid spreading or 

 reflexed herbaceous but indurated and pungent tip. Receptacle flattish, densely 

 bristly. Achenes glabrous ; pappus of numerous flattish barbellate bristles 

 united into a ring at the base and deciduous together. — Thistle-like tall stout 

 prickly herbs with sinuate-lobed or pinnatifid mottled leaves and large solitary 

 heads of purple flowers. (Derived from aiXv^os, the ancient Greek name of an 

 edible-stemmed thistle. ) 



1. S. MARiXxcM (L.) Gaertn. (Lady's Thistle.) Stout and nearly gla- 

 brous annual or biennial, with large mottled amplexicanl leaves variously lobed 

 and prickly on the margin. (Mariana Hill.) — An occasional escape from gar- 

 dens, or weed on ballast and waste grounds. (Introd. from s. Eu.) 



86. CENTAUREA L. Star Thistle 



Heads many-flowered ; flowere all tubular, the marginal often much larger 

 (as it were radiate) and sterile. Receptacle bristly. Involucre ovoid or globose, 

 imbricated ; the bracts margined or appendaged. Achenes obovoid or oblong, 

 compressed or 4-angled, attached obliquely at or near the base ; pappus setose 

 or partly chaffy, or none. — Herbs with alternate leaves ; the single heads rarely 

 yellow. (KevTavpirj, an ancient Greek plant-name, poetically associated with 

 Chiron, the Centaur, but mthout wholly satisfactory explanation.) 



Bracts of the involucre (or at least the outer ones) terminated by a definite 

 elongate rigid spine ; annuals. 



SteEQS not winged 1. C. Calcitrapa. 



Stems winged. 

 Spines of the involucre stout, straw-colored, 12-13 mm. long ... 2. C. soUtitialia. 

 Spines of the involucre slender, purplish, 6-9 mm. long .... 3. C. melitensiti. 

 Bracts not spinose-tipped, or merely with short firm tip hardly longer than 

 the lateral teeth, cilia, or fringe. 

 Bracts entire or merely with irregularly denticulate or lacerated (not regu- 

 larly toothed or pectinate) margin " A. C. Jacea. 



