MONOPETALOUS EXOGENOUS PLANTS. 3G1 



pus sometimes wanting, when present of one or two rows 

 of rough bristles. 



C. Americana. Stem 2°-4° high, erect, sparingly 

 branched; lower leaves oblong-ovate, repand-dentate, 

 upper ones lanceolate, acute, sessile, glabrous ; heads few 

 or solitary, very large ; ray-floiuers twice longer than the 

 disk ; scales with pectinate-pinnate, reflexed appendage. 

 Floivers large, showy pale-purple heads. Red River. — 

 Engelmann. 



* Leaves sessile. 



t Scales of the involucre tipped with spreading spines. 



C. ViRGiNiANUM. Stem 2°-3° high, tall, branching, 

 commonly hairy ; leaves with scattered hairs above, pubes- 

 cent or at length nearly smooth beneath, bristly ciliate on 

 the margins, deeply pinnatifid; the lobes lanceolate, 2-3- 

 toothed, spiny; scales of the involucre unarmed, webby, 

 viscid; flowers purple; heads V in diameter. 



Sub-order II. Labiatiflorse, not represented in any 

 floral report. 



Sub-order III. Liguliflorae. 



Tribe VII. Cichoracese. Style cylindrical above 

 and pubescent, like the rather obtuse branches; the stig- 

 matic lines terminating below or near the middle of the 

 branches. — Plants with milky juice; leaves alternate. 



KRIGIA, Schreb. 



Heads 15-30-flowered; scales of the involucre 6-15, 

 somewhat in 2 rows, equal ; receiotacle naked ; achenia top- 

 shaped, 5-angled ; pappus double, the outer of 5 broad 

 chatfy scales, the inner of 5 rough bristles. — Small annual 

 herbs, branching at the base, with naked peduncle-like 

 stems, each terminated by a small head of yellow flowers ; 

 leaves chiefly radical, mostly lyrate or toothed. 



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