234 compositjE. (composite family.) 



whitened uith loose webliy hairs beneath when young, deeply pinnatifid, the divtsiom 

 lanceolate, acute, cut-lobed, prickly-pointed ; scales of the webby and glutinous invo- 

 lucre closely appressed, pointless or barely mucronate; flowers purple. IJ.— 

 Swamps and low woods ; common. Aug. 



8. C. pniniluin, Spreng. (Pasture Thistle.) Stem low and stout 

 (l°-3° high), hairy, bearing 1-3 very large heads (Ij' M'oad), which are some- 

 what leajy-bracted at the base ; leaves lanccolatE-oblong, partly clasping, green, 

 somewhat hairy, pinnatifid, with short ana cut very pricHy-margined lobes; outer 

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

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

 coast. July. 



9. C. horridulum, Michx. (Yellow Thistle.) Stem stout {1° - i^ 

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

 lanceolate, pinnatifid, the short toothed and cut lobes very spiny with yellowish 

 prickles ; heads large (I'-l^' broad), surrounded at the base by an involucrate whorl 

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

 scales of the involucre ; flowers pale yellow, often turning purple in fading. -— 

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

 June - Aug. 



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

 smooth : heads imperfectly dicecious. 

 10 C. AKvfiNSE, Scop. (Canada Thistle.) Low, branched ; roots ex- 

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

 beneath, sinuate-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 diSicult to eradicate. July, Aug. 

 (Nat. from Eu.) 



6§. CARDirUS, Toum. Plumelbbs Thistle. 



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

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



1. C. NtjTANS, L. (Musk Thistle.) Leaves decurrent, sinuate, spiny; 

 heads solitary, drooping ; flowers purple. @ — Fields neai- Hanisburg, Penn., 

 Prof Porter. (Adv. from Eu. ) 



69. ONOP6r»ON, ValU. Cotton Thistle. 



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

 tipped with a lanceolate prickly appendage. Receptacle deeply honeycombed. 

 Achenia 4-angled, wrinkled transversely. Bristles of the pappus numerous, 

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

 herbs, with the stems winged by the decurrent base of the lobed and toothed 

 somewhat prickly leaves. Heads large : flowers purple. 



1. O. acAntiiium, L. Stem (2°-4° high) and leaves cotton-woolly; scales 

 Vnear-awl-shaped. ® — Boad-sides, New England. (Adv. from Eu.) 



