398 COMPOSITE. Cnicus. 



heads ; tlie flowers red, purple, or rose-color, rarely white or yellowish, in summer. 



Many hybridize ! — L. Gen. ed. 6, 409 (where the clmr. is pappus plumosus, and 



in Spec. ed. 2, two years earlier, G. benedictus is referred to Centaurea) ; Willd. 



Spec. iii. 1G62; Benth. & Hook. Gen. ii. 468. Girsium, DC. Fl. Fr. ed. 3, iv. 



110, & Prodr. vi. 634, not Tourn. 



§ 1. Naturalized from Europe : one species with dioecious heads. 

 «=s» C. ARTENSis, HOFFM. (CANADA Thistle). Perennial and spreading by creeping root- 

 'stocks, a foot or two high, coryrabosely branching, usually glabrate and green: stem and 

 branches wino-less: leaves lanceolate, pinnatifid and toothed, furnished with abundant weak 

 pricldes ■ heads loosely cymose, less than inch high, dioecious ; in male plant ovate-globular, 

 and flowers (rose-purple)' well exserted; in female oblong-campanulate and flowers less pro- 

 jecting : bracts of involucre all appressed, short, and with very small weak prickly points : 

 only abortive anthers to the female flowers. — Fl. Germ. iv. 180 ; Pursh, Fl. ii. 506. Serratula 

 arrensis, L. Spec. ii. 820 ; Fl. Dan. t. 644. Carduus arvensis, Curt. Fl. Loud. t. 57 ; Engl. 

 Bot. t. 975. Ctrsium arrense, Scop. Fl. Cam.; DC. Prodr. vi. G4.3; Torr Fl. N. Y. i. 408, 

 t. 61 ; Reichenb. Ic. Fl. Germ. t. 842. Breea arvensis, Less. Syn. 9. — IMeadows, pastures, 

 and waste grounds, from Newfoundland through the Northern and Middle Atlantic States : 

 too common weed. (Xat. from Eu.) 

 s*!»jC. lanceolAtus, Hoff.m. 1. c. (Common Thistle of fields.) Biennial, 3 or 4 feet high, with 

 large heads (almost 2 inches high) terminating somewhat leafy branchlets, cottouy-tomen- 

 tose when young, becoming green, more or less villous or hirsute : leaves lanceolate, deeply 

 pinnatifid and with lanceolate lobes, rigidly prickly; upper face strigose-setulose ; base 

 decurrent on the stem into interrupted prickly wings ; bracts of involucre arachnoid-woolly, 

 lanceolate and mostly attenuate into slender and rigid prickly-pointed spreading tips : flow- 

 ers rose-purple, hermaphrodite. — Willd. Sjjec. iii. 1666 ; Pursh, 1. c. Carchms lauceolatus, L. ; 

 Engl. Bot. t. 107; Fl. Dan. t 1173. Cirsium lanceolntiim, Scoji. 1. c. ; DC. 1. c. ; Reichenb. 

 Ic. Fl. Germ- t. 826. — Pastures and waste grounds, Newfoundland and Canada to Georgia 

 (very common northward) ; also in <_>regon. (Nat. from Eu.) 



§ 2. Indigenous species, all but one Alaskan species endemic, all or mostly 

 biennials. 



* Bracts of the ovoid or hemispherical involucre appressed-imbricated and the outer successively 

 shorter, all with loose and dilated fimbriate or lacerate white-scarious tips. — Edienak^ 

 Cass., DC. 



C. Americanus, Gray. A foot or two high, branching above : branches bearing solitary 

 or scattered naked heads: leaves white-tomentose beneath, lanceolate or broader, sinuately 

 pinnatifid, or some merely dentate, others pinnately parted, weakly prickly : Iwnh erpct. inch 

 high ■ principal bracts of the involucre naked-edged or merely fimbriate-ciliate (not setose- 

 spinuliterous) below, and the dilated scarious apex as broad as long, fimbriate-lacerate, 

 tipped with barely exserted cusp or mucro ; innermost with lanceolate nearly entire scarious 

 tips: flowers ochroleucous : stronger pajjiius-bristles dilated-clavcUate at tip. — Proc. Am. 

 Acad. xix. 56, without char. C. carlirioidex, var. Amrrirdiiiis, (iray, Proc. Am. Acad. x. 48, 

 & Bot. Calif, i. 420, excl. sj'n. Nntt., &c. Echenais cnrliiiiiuhs, var. nutans, (iray, Proc. -Vcad. 

 Philad. 1863, 69. — Lower mountains of Colorado and New Mexico to the coast of California. 

 (A hylirid with C. undnhitns? with red-purple flowers and purplish tips to involucral bracts, 

 is from Pinos Altos Mountains, New Mexico, Greene.) 



# * Bracts of the involucre mostly loose, not appressed-imbricated nor rigid, tapci-ing gvacluaUy 

 from a narrow base to a slender-prickly or nuiticous apex; outer not very much shorter than 

 the inner, wholly destitute of dorsal ghmdular ridge or spot, 



-I— Some with scarious or fringed tip or margins, at least tlic innermost, sliglitly or not at all 

 prickly-pointed (except accc^suiy leafy ones): leaves not decurrent on the stem, moderately 

 prickly: Rocky Jlountuin and Westeru species. 



C. Pairryi, Gray, (irccn, lightly arachnoid and villous when young, 2 feet or so high : leaves 

 lanceolate, sinuate-dentate: heads (inch high) scvcnil and s|)i('iitrly glomerate ov more race- 

 mosely paniculate, more or less liractooso-lcafy at base : accessory and outer proper bracts 

 or sonic of them pectiuately fimbriate-ciliate down the sides, innermost with more or less 



