234 COMPOSITE. (COMPOSITE FAMILY.; 



whitened with hose webby hairs beneath when young, deeply pinnatifid, the 

 binceolate, acute, eut-lobed, prickly-pointed; scales of the webby and glutinous invo- 

 lucre closely appressed, pointless or barely mucronate; flowers purple, ty 

 Swamps and low woods ; common. Aug. 



8. C. imiciiliiEii, Spreng. (PASTURE THISTLE.) Stem low and stout 

 l-3 high), hairy, bearing 1-3 very large heads (l' broad), which are some- 



:rluit leafy-bracted at the base ; leaves lanceolate-oblong, partly clasping, green, 

 somewhat hairy, pinnatijid, with short and cut very prickly -margined lobes; outer 

 scales of the involucre prickly-pointed, the inner very slender ; flowers purple or 

 rarely white (fragrant, 2' long). (2) Dry fields, Maine to Perm., near the 

 coast. Also Illinois and westward ; common. July. 



9. C. laorridulnm, Michx. (YELLOW THISTLE.) Mem stout (l-4 

 high), webby-haired when young; leaves partly clasping, green, soon smooth, 

 lanceolate, pinnatijid, the short toothed and cut lobes very sjriny with yellowish 

 prickles ; heads large (!'- l' broad), surrounded at the base by an involucrate whori 

 of leaf-tike and very prickly bracts, which equal or exceed the narrow and unarmed 

 scales of the involucre ; flowers pale yellow, often turning purple hi fading. 

 Sandy fields, &c., Massachusetts to Virginia, and southward, near the coast. 



. June -Aug. 



* # * Outer scales of the appressed involucre barely prickly-pointed: filaments nearly 

 smooth : heads imperfectly dioecious. 



10. C. ARVEXSE, Scop. (CANADA THISTLE.) Low, branched ; roots ex- 

 tensivcly creeping; leaves oblong or lanceolate, smooth, or slightly woolly 

 beneath, sinnatc-pinnatifid, prickly-margined; heads small and numerous ; flow- 

 ers rose-purple. 1[ Cultivated fields and pastures; common at the North : a 

 most troublesome weed, which it is extremely difficult to eradicate. July, Aug. 

 (Nat. from Eu.) 



6. CARDUUS, Tourn. PLUMELESS THISTLE. 



Bristles of the pappus naked (not plumose), merely rough or denticulate. 

 Otherwise as in Cirsium. (The ancient Latin name.) 



1. C. xfjTANS, L. (MosK THISTLE.) Leaves decurrent, sinuate, spiny: 

 heads solitary, drooping; flowers purple. (2) Fields near Harrisburg, Penn., 

 Prof. Porter. (Adv. from Eu.) 



69. ONOP6RDON, Vaill. COTTON THISTLE. 



Heads and flowers nearly as in Cirsium. Scales of the involucre coriaceous, 

 tipped with a lanceolate prickly appendage. Receptacle deeply honeycombed. 

 Achcnia 4-an.jlcd, wrinkled transversely. Bristles of the pappus numerous, 

 slender, not plumose, united at the base into a horny ring. Coarse, branching 

 hrrbs, with the stems winged by the dccurrcnt base of the lobed and toothed 

 somewhat prickly loaves. Heads large : flowers purple. 



1. O. ACANTHI KM, L. Stern (2 -4 high) and leaves cotton-woolly; scales 

 Road-sides. New England. (Adr. from Eu.) 



