398 COMPOSITE. 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 plumosus, and 

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

 Spec. iii. 1662; Benth. & Hook. Gen. ii. 468. Oirsium, DC. Fl. Fr. ed. 3, iv. 

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



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



C. ARVENSIS, HOFFM. (CANADA THISTLE). Perennial and spreading by creeping root- 

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

 branches wingless : leaves lanceolate, pimiatifid and toothed, furnished 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-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 

 arvensis, L. Spec. ii. 820; Fl. Dan. t. 644. Carduus an-ensis, Curt. Fl. Loud. t. 57; Eugl. 

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

 t. 61 ; Reichenb. Ic. Fl. Germ. t. 842. Dreca arvensis, Less. Syu. 9. Meadows, pastures, 

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

 too common weed. (Nat. from Eu.) 



C. LANCEOLAxus, HoFFM. 1. c. (COMMON THISTLE of fields.) Biennial, 3 or 4 feet high, with 

 large heads (almost 2 inches high) terminating somewhat leafy branchlets, cottony-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. Spec. iii. 1GGG ; Pursh, 1. c. Carduus lanccolatiis, 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.) 



t 



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. Echenais, 

 Cuss., 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 piunately parted, weakly prickly : heads erect, inch 

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

 spinuliferous) 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 pappus-bristles dilated-clavellate at tip. Proc. Am. 

 Acad. xix. 56, without char. C. cnrlinoidrs, var. Americanus, Gray, Proc. Am. Acad. x. 48, 

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

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

 (A hybrid with C. unditlatus? 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, tapering gradually 

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

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



-t Some with scariotis 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: Rocky 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 spicatcly 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 lesa 



