COMPOSITE FAMILY. 255 



64. ARCTIUM, BURDOCK. (Probably Greek, bear, from the spiny 

 involucre.) (p. 222.) 



A. Ldppa, Linn. Common B. Leaves large, loosely cottony beneath, 

 or somewhat naked, the lov^er heart-shaped, upper ovate ; common in 

 manured soil and barnyards. Var. minor is smaller and smoother, with 

 leaves tapering at the base, often cut-toothed or cleft. Flowers mostly 

 purple, all summer and autumn. ® (D 



65. CNICUS, THISTLE. (Old name.) Flowers purple or pink, 

 occasionally yellow or white, in summer, (g) ^ (pp. 221, 222.) 



« All the scales of the head armed with spreading prickly tips. 



C. /anceo/atus, Hoffm. Common or Bull T. Nat. from Eu. in pastures ; 

 the base of the rough, deeply pinnatifid leaves running down the stem in 

 lobed prickly wings ; flowers purple. (2) 



* * All or most of the scales of the head appressed, the innermost not 

 prickly-pointed, the outer with a short prickle or point, or none. 



•*- Leaves green both sides or a little cottony or cobwebby underneath. 



C. arvensis, Hoffm. Canada T. A vile pest in fields and meadows 

 N., nat. from Eu. ; spreading by deep, running roots as well as by seed ; 

 numerous short-peduncled heads only 1' long, with rose-purple flowers ; 

 leaves moderately pinnatifid, weak-prickly, y. 



C. horridulus, Pursh. Yellow T. Leaves very prickly, rather large 

 heads surrounded at base by an involucre or whorl of leaf-like very 

 prickly bracts ; flowers yellowish or purplish. Sandy fields near the 

 coast, Mass., S. 



C. ptimilua, Torr. l°-8° high, with lance-oblong pinnatifid leaves, 

 single very large heads (almost 2' across) of fragrant (purple or rarely 

 white) flowers, sometimes leafy-bracted at base. Me. to Pa. (|) 



C. miiticus, Pursh. Swamps and low ground ; S°-S° high, with 

 deeply divided leaves, few or no prickles, and rather large naked heads, 

 most of the scales pointless ; flowers purple. 2/ 



H- t- Leaves white-cottony underneath ; flowers purple, rarely white. 



C. altisBimua, Willd. 3°-10° high, branching, leafy up to the rather 

 small heads, the oblong leaves wavy or only slightly pinnatifid, except the 

 lowest, d) % Mass. to Minn., S. 



Var. discolor. Gray. 8°-6° high, branching and leafy, with rather 

 small heads, and deeply pinnatifid leaves, green above, white beneath, 

 their lobes narrow and prickly pointed. @ 



C. Virginiinus, Pursh. Stems rather simple, l°-3° high, ending in a 

 long naked peduncle ; leaves lanceolate and slightly or not at all pinnati- 

 fid ; head small. % Plains and barrens, Va., W. and S. 



66. CYNARA, ARTICHOKE. (Ancient Greek name.) 2/ (p- 222.) 



C. Cardunculus, Linn. Cardoon. Leaves deeply and compoundly 

 divided and prickly, the less fleshy scales of the head prickly-tipped ; the 

 fleshy leafstalks and midrib eaten after being blanched in the manner of 

 celery. Strong thistle-like plants, 4°-6°. Eu. 



C. ScoLTMUs, Artichoke, has less compound leaves, the ovate and 

 usually pointless scales of the involucre and the receptacle of the young 

 flower heads fleshy, and edible when cooked. A modification of the 

 above. 



