COMPOSITE.. 218 



1. C. ARVE'NSE. Scop. Cnicus arvensis. P. 

 Leaves sessile, pinnalifid, spinous; stem panicled; involucr erounA or ovate, 



with minute spines, scales close pressed, ovate-lanceolate. A very cominou 

 thistle in fields, roadsides and waste places. It is one of the severest pests of 

 the fanner, requiring his constant vigilance to extirpate it from his fields. 

 In Enorland it is called cursed thistle. Root creeping, very long and e.xceed- 

 ingly tenacious of life. Stem 3 feet high, with a branching panicle at top. 

 Leaves alternate, thickly beset with thorns. Flowers rather small, purple, 

 the involucre nearly thornless, and is the only part of the plant that can be 

 safely handled. July. Per. Canada Thistle. 



2. C. Dl'SCOLOR. Spreng. Cnicus discolor. Muh. 

 Leaves sessile, pinnatifid, rough-haired, downy beneath, the segments 2- 



lobed. divaricate, spinosc; involurre globose, the scales ovate, appressed, with 

 spreadmg spines at the tips. A slender thistle, 3 — 5 feet high, much branch- 

 ed, and Icjify at the summit. Found in thickets. Heads terminating the 

 branches, an inch in diameter, with reddish purple corollas. July, Aug. 

 Bien. Tall. Thistle. 



3. C. MU'tiCUM. Mx. Cnicus glutinosus. Bw. 

 Leaves pinnatifid with divaricate segments ; involucre ovate, with unarmed, 



villous-arachnoid, glutinous scales. A fine-looking thistle found in damp 

 soils. Stem branching, 3—7 leet high. Leaves armed with spines at each 

 angle. Heads half an inch in diameter, with deep purple corollas, the scales 

 webbed and glutinous on the back. Aug. Sept. Bien. Glutiiwus Thistle. 



4. C. HORRi'dULUM. Mx. Cnicus horridulus. Etc. 

 Leaves sessile, pinnatifid, acutely cut, spinose ; heads invested with an 



external involucre of about 20 very spinose bracts; .wa/e^ unarmed. Found 

 in meadows, &-C. The stem is 1 — 3 feet high, invested with wool. Leaves 

 somewhat clasping, woolly and hairv, armed with stiff spines. Heads large, 

 with yellowish-white corollas surrounded by a whorl of lanceolate or linear 

 leaflets tipped with stiffthorns, the scales webbed. Aug. Bien. 



Yellow Thistle. 



5. C. PU'mILUM. Spreng. Cnicus odoratus. JW;/A. 

 Hairy; /cares green on both sides, clasping, oblong-lanceolate, pinnatifid, 



the seo-ments irregularly lobed,ciliate, spinose ; involucre round ovate, spinose, 

 naked" A common, low, turgid thistle in roadsides, pastures, «Si:c. Stem 

 1— -2 feet high, stout, striate, with 1—3 very large heads of fragrant, purple 

 flowers. Aug. Bien. Pasture Thistle. 



6. C. LANCEOLA'TUM. Scap. Carduu."* lanceolatus. L. Cnicus Uuiceolatum. P. 

 Leaves decurrent, pinnatifid, hispid, the segments divaricate and spinose ; 



involucre ovale, villous ; scales lanceolate, spreading. Common in borders of 

 fields, roadsides, &c., always distinguished by the decurient leaves. Stem 



3 4 feet high, winged by "the decurrent leaves which are white and woolly 



beneath, arnied with formidable spines at all points. Flowers numerous, 

 large, purple. Involucre scales webbed, each ending in a spine. Ju|y— 

 Sept. Bien. Common Thistle. 



5 3. LAPPA. 

 Heads discoid, homogamotis: involucre globose, the scales 

 imbricated and hooked at the extremity ; receptacle bri:jtly ; 

 pa[ipu3 bristly, scabrous, caducous. 



