CENT AU RE A 



COMPOSITE 385 



Subtribe ii. Centauries DC. Prodr. ri. 557. Achates more or 

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

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

 91 OENTAUREA L. Gen. n. 984. 



Perennial or annual herbs with alternate leaves and large or 

 middlesized heads of tubular and various colored flowers. Invo- 

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

 pressed, timbrillate. 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, obliquely 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 spinnlose 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- 

 nat fid ; uppermost somewhat iuvolucrate-crowdeJ at the base of the sessile 

 heads: principal bracts of the involucre armed with a widely spreading 

 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 California. 

 Sparingly introduced from Europe. 



C. Mel tensis L. 1. c. Stems erect, 1-4 feet high, paniculately bran- 

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

 lyrate pinnatifid; cauline^lanceolate or linear, mostly entire, narrowly 

 decurrent on the branches : heads sessile or 1- or 2-leaved at base, prin- 

 cipal bracts of the involucre bearing a slender spreading spine of about 

 their own length, which is pectinately spinulose toward the base; inner- 

 most with simply spinescent tips; outermost usually with the central 

 spine reduced and the spinules palmate : corollas yellow : achenes lightly 

 costate : pappus of very unequal rigid bristles or sqnamellae. Rather com- 

 mon in fields and waste places British Columbia to California and Arizona. 

 Naturalized 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 na- 

 ked 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 fields 

 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 flowers solitary at the 



