CENTAUREA COMPOSITAE 385 



Stibtribe it, Centaurieae BC, Prodr. vi.557. Achenes more or 

 less compressed or qttadrangular. Heads globular or ovoid. Pap- 

 pus of indefinite, few or many, bristles or narrow paleae. 

 91 CENTAUREA L. Gen. n. 984. 

 Perennial or annual herbs with alternate leaves and large or 

 middle-sized heads of tubular and various colored flowers. Invo- 

 lucre ovoid or globose, its bracts imbricated in many series, ap- 

 pressed, fimbrillate, or dentate. Receptacle flat, densely bristly. 

 Marginal flowers usually neutral and larger than the central per- 

 fect and. fertile ones, or flowers all perfect in some species. Co- 

 rolla-tube slender, the limb regular or oblique, 5-cleft or 5-lobed, 

 the segments sometimes appearing like rays. Anthers sagittate 

 at base. Style-branches short, somewhat connate, obtuse. 

 Achenes compressed or obtusely 4-angled, usually smooth and 

 shining, o'bliquely or laterally attached to the receptacle, sur- 

 mounted by a disk with an elevated margin. Pappus of several 

 series of bristles or scales, rarely none. 



* At least some of the involucral bracts armed with a rigid spine 

 or prickle and also spinulose along its sides or base: cartilaginous ap- 

 pendages of the anthers commonly elongated and connate. 

 C. CALCITRAPA L. Sp. 917. (Star Thistle.) Low, much branched 

 diffusely spreading, green, glabrate or hairy: leaves narrow, laciniate-pin- 

 natifid; uppermost somewhat involucrate-crowded at the base of the ses- 

 sile heads : principal bracts of the involucre armed with a widely spread- 

 ing very long and rigid spine which bears 2 or 3 spinules on each side at 

 base : corollas purple or pinkish : pappus none. Vancouver Island to Cali- 

 fornia. Sparingly introduced from Europe. 



C. Melitensis L. 1. c. Stems erect, 1-4 feet high, paijiculately branched, 

 cinereous-pubescent, somewhat woolly when young: radical leaves lyrate 

 pinnatifid; cauline lanceolate or linear, mostly entire, narrowly decurrerit 

 on the branches : heads sessile or 1- or 2-leaved at base, principal bracts 

 of the involucre bearing a slender spreading spine of about their own 

 length, which is pectinately spinulose toward the base; innermost with 

 simply spinescent tips ; outermost usually with the central spine reduced 

 and the spinules palmate : corollas yellow : achenes lightly costate : pap- 

 pus of very unequal rigid bristles or squamellae. Rather common in fields 

 and waste places, British Columbia to California and Arizona. Natural- 

 ized from Europe. 



■*" ■*" Bracts of the involucre unarmed, most of them terminated 

 by a scarious discolored fimbriate-ciliate or lacerate appendage. 

 C. Cyanus L. Sp. 911. (French Pink, Blue Bottle.) Slender branch- 

 ing annual : stems 1-6 feet high, whitened when young with floccose 

 wool : leaves linear, entire, or the lower toothed or pinnatifid : heads . 

 naked on slender peduncles : involucral bracts rather narrow, furnished 

 with short scarious teeth : marginal flowers neutral, with much enlarged 

 radiform blue or white varying to pink, purple or brown corollas : pappus 

 of unequal bristles about the length of the achene. Very common in 

 fifelds Brit. Columbia to California. Introduced from Europe. 

 92 CNICUS L. Sp. 826. (Blessed Thistle.) 

 Annual herbs with alternate sinuate or pinnatifid prickly leaves, 

 and large sessile heads of yellow tubular flowprs solitary at the 



