Centaurea. COMPOSITiE. 455 



lowest involucral scales scarious and obtuse : pappus none. DC. prodr. 

 6. p. 597. 



Naturalized in Virginia near Norfolk ! — (l) (D 



C. Caroliniana, Walt, is doubtless Stokesia cyanea, VHer. 



170. CNICUS. Vaill. ; Gcertn. fr. t. 162 ; DC. diss. Sf prodr. I. c. 



Heads many-flowered ; the ray -flowers sterile, slender, nearly equal to the 

 disk. Scales of the ovoid involucre coriaceous, appressed, produced into a 

 long and rigid pinnated spinose appendage. Receptacle densely clothed with 

 capillary bristles. Achenia terete, smooth, strongly striate, with a large lat- 

 eral basilar areola. Pappus triple ; the exterior, or rather margin of the 

 fruit, of 10 very short corneous teeth ; the intermediate of 10 elongated sub- 

 ulate-fihform rigid bristles; the inner of 10 short bristles; the three series 

 regularly alternating with each other.— An annual slightly woolly or 

 villous branching herb (of uncertain nativity) ; with clasping and some- 

 what decurrent undivided subpinnatifid leaves, and bracteate heads. 

 Corolla yellow. 



C. benedictus (Linn.) — Centaurea benedicta, Linn. spec. ed. 2. p. 1296. 



Sparingly introduced, but scarcely naturalized in New York, &c. Louis- 

 iana, Mr. Leavenworth! It has also been found in Mexico and Chili, to 

 which it was probably brought from Southern Europe. 



Subtribe 3. Carduines:, Less., J>C.— Heads discoid, homogamous, 

 m.any-flowered ; the flowers all similar, perfect or dioecious. Scales of the 

 involucre imbricated in several series, often spinose at the apex. Corolla 

 usually curved outwards, the exterior lobe often deeper cleft than the others. 

 Anthers slightly or not at all caudate. Achenia glabrous, with a terminal 

 areola. Pappus composed of slender scabrous or plumose bristles, which 

 are often united into a ring at the base. 



171. CIRSIUM. Tourn. ; DC. fi. Fran. ed. 3, &f jnodr. 6. p. 643. 



Heads many-flowered ; the flowers perfect and similar, rarely subdioe- 

 cious. Scales of the involucre imbricated in numerous series, mostly cuspi- 

 date or tipped with a prickle. Receptacle bristly. Corolla regularly or 

 often unequally 5-cleft. Anthers more or less produced and lacerate at the 

 base : filaments often hairy. Branches of the style concreted nearly to the 

 apex. Achenia oblong, compressed, glabrous, not ribbed. Bristles of the 

 pappus numerous and somewhat unequal, united into a ring at the base, 

 plumose, merely denticulate (and the stronger ones often slightly clavellate) at 

 the apex. — Herbs, with sessile or decurrent alternate leaves, which are often 

 pinnatifid ; the margins and teeth usually spinose. Heads subglobose. 

 Corolla purple, reddish, or ochroleucous. — Thistle. 



