MONOPETALOUS EXOGENOUS PLANTS. 327 



2°-4° high, branched, pubescent, somewhat viscid ; leaves 

 toothed or entire, pubescent, or smoothish beneath, the 

 lower sometimes opposite. 



BRICKELLIA, Ell. 



Herbs with opposite leaves, three-ribbed and dotted; 

 heads large, purple, in terminal corymbs ; scales of involu- 

 cre imbricated, outer ones shorter ; receptacle flat, naked ; 

 corolla 5-toothed ; aclienia cylindrical, 10-striate : pappus 

 a single row of bearded bristles. Perennial. 



B. CORDIFOLIA, Ell. Heads large, from 30-40-flowered ; 

 aclienia nearly smooth; stem erect, branching; leaves 

 ovate, serrate, mostly cordate, petioled, the upper ones 

 mostly alternate. Stem 2°-4° high ; floioers conspicuous 

 and gay. 



EUPATOEIUM. Thoroughwort. 



Herbs, resinous dotted, opposite or whorled leaves; 

 floioers purple and white; -i?it'0^z^cre bell-shaped or cylin- 

 drical ; scales in a single row or imbricated in two or more 

 rows; receptacle flat, naked; corolla 5-toothed; aclienia 

 5-angled, the sides smooth ; pappus a single row of rough 

 bristles ; lieads corymbed. 



* Scales of the involucre imrplish, scarious, obtuse, imbricated in several roios^ the 

 outer ones much shorter ; leaves whorled; flowers 'purple. 



E. PURPUREUii. Stem simple, tall, often dotted ; leaves 

 3-6 in a whorl, varying from lanceolate to ovate, 

 coarsely serrate, roughish ; corymbs large, compound; 

 heads 5-10-flowered. Stem 3°-io° high, solid or hollow, 

 even or grooved, smooth or pubescent. 



** Scales of the involucre green or white, imbi'icnted in several rows ; heads 

 5-10-flowered ; leaves, achenia, etc., ^dotted loith resinous glands; flowtrs 

 white. 

 t ffeadS^-floioered ; leaves undivided, sessile, or yiarrowed into a static-like base. 



E. HYSSOPiFOLiUM, L. Stem 2°-o° hidi : leaves lanceo- 



