274 COMPOSITE. (CO-MTOSITE FAMILY.) 



■t- -t- Leaves green both sides, or onhj with loose cobwehhi/ hairs vnderncalh : scales of 

 the involucre scarccli/ pricUy-pointeci : heads large. 



7. C. muticum, Jlichx. (Swamp Thistle.) Stem tall (3°-8°high), 

 angled, snioutliisli, jjunick-d at the summit, the branches sparingly leafy and 

 bearing single or few rather large naked heads ; leaves somewhat hairy above, 

 whitened with louse tvdJii/ hairs beneath wiien young, deejilji jiinmttijid, tlte divisions 

 lanceolate, acute, cut-Iobcd, j)rickly-pointed ; scales of the icehhij and glutinous invo- 

 lucre closely apprcssed, pointless or barely niucronate ; flowers purple ; root per-, 

 cnnial. — S\vaini)s and low woods : common. 



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

 (l°-3° liigli). Iiaiiy, bearing 1 -3 very large hauls (li' broad), which are some- 

 ivhat leafif-bracted at the base ; leaves green, lanceolate-oblong, partly chisping, 

 sometrhat hairi/, pinnatijid, with short and cut very jiric/clij-margined lobes ; outer sades 

 of the involucre pricklij-jioiiitcd, the inner very slender ; flowers purple or rarely 

 white (fragrant, 2' long) ; root biennial. — Dry fields, Maine to Penn., near the 

 coast, Illinois and westward : common. 



9. C. horridulum, Michx. (Yellow Thistle.) Stem stout (l°-4o 

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

 lanceolate, pinnatijid, the short toothed and cut lolxs veri/ spiny with yellowish 

 prickles; heads (l'-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 or purple. — Sand}' fields, Massachu- 

 setts to Virginia, and southward, near the coast. 



* * * Outer scales of the appressed involucre barely prickly-pointed : f laments nearly 

 imooth : heads imperfectly dioecious, sm(dl and numerous. 



10. C. ARVENSE, Scop. (Canada Thistle.) Perennial, the roots exten- 

 sively creeping ; leaves oblong or lanceolate, smooth, or slightly woolly beneath, 

 sinuate-pinnatifid, prickly-margined ; flowers rose-purple. — Cultivated fields, 

 pastures, and roadsides : common at the North ; a most troublesome weed, ex- 

 tremely difficult to eradicate. (Nat. from Eu.) 



68. CARDUTJS, Tourn. Plumeless Thistle. 



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

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



1. C. NUTANS, L. (Musk Thistle.) Biennial; leaves decurrent, sinuate, 

 spiny; heads solitary, drooping; flowers purple. — Fields near Ilarrisbiirg, 

 Penn.sylvania, Prof Poftei: (Adv. from Eu.) 



69. ONOPORDOW, Vaill. Cotton or Scotch Thistle. 



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

 tipped with a lanceolate ))rickly appendage. Receptacle deeply honeycombed. 

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

 slender, not ))lumose, united at the base into a horny ring. — Coarse, branching 

 annuals, or biennials, with the stems winjred l)y the decurrent base of tin; lobed 

 and toothed somewhat prickly loaves. Heads large- flowers purple. (The an- 

 cient Greek name of the plant.) 



