398 COMPOSITiE. Cnicus. 



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

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

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

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

 11 0, & Prodr. vi. 634, not Tourn. 



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



C. AUVENSis, HoFFM. (Canada Thistle). Pcreuuiiil and spreading by creeping root- 

 stocks, a foot or two high, corymbosely branching, usually glahrate and green : stem and 

 branches wingless : leaves lanceolate, piunatifid and toothed, furnislied with abundant weak 

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

 and flowers (rose-purple) well exserted ; in female oblong-campannlate 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. Sermtula 

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

 Bot. t. 975. Cirsium arvense, Scop. Fl. Carn. ; DC. Prodr. vi. 643; Torr. Fl. N. Y. i. 408, 

 t. 61 ; Keichenb. Ic. Fl. Germ. t. 842. Breea cn-vensis, Less. Syu. 9. — Meadows, pastures, 

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

 too common weed. (Nat. from Eu.) 



C. i.anceolAtus, Hoffm. 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 interrujited 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. Spec. iii. 1666 ; Pursh, 1. c. Carduux lanceolalus, L. ; 

 Engl. Bot. t. 107; Fl. Dan. t 1173. Cirsium lanceolatum, Scop. 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 Oregon. (Nat. from Eu.) 



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

 biennials. 



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

 shorter, all willi loose and dilated tinibriate or hucrate white-scarious tips — Edienais, 

 Cass., DC. 



C. Americanus, Gray. A foot or two high, branchmg 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 : heads erect, inch 

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

 s])iuuliferous) below, and the dilated scarious apex as broad as long, fimbriate-l.acerate, 

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

 tips: flowers ochroleucous : stronger pappus-bristles dilated-clavcllate at tip. — Proc. Am. 

 Acad. xix. 56, M'ithout char. C. carlinoides, var. Americanns, Gray, Proc. Am. Acad. x. 48, 

 & Bot. Calif, i. 420, excl. syn. Nutt., &c. Echenais carlinoides, var. nutans, Gray, Proc. Acad. 

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

 (A hybrid with C. undulatus? with red-purple flowers and purpli.sh tips to involucral l)racts, 

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



* * Bracts of the involucre mostly loose, not apprcsscd-imbricated nor rigid, tapering gradually 

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

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



+- Some with scarious or fringed tip or margins, at least the innermost, .slightly or not at all 

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

 prickly : Hocky Mountain and Western species. 



C. Parryi, Gray. Green, lightly arachnoid and villous when young, 2 feet or so high : leaves 

 lanceolate, sinuate-dentate: heads (inch high) several and spicately glomerate or more race- 

 mosely paniculate, more or less bracteose-leafy at base : accessory and outer proper bracts 

 or some of them pectinately fimbriate-ciliate down the sides, innermost with more or less 



