MONOPETALOUS EXOGEXOUS PLANTS. 357 



pappua none. — Perennial lierbs ; leaves alternate, com- 

 monly pinnately divided ; heads small, corymbose. 



A. MILLEFOLIUM, L. SteiHS (1° high) simple, pubescent, 

 tufted; leaves lanceolate, bipinnatilid, the division linear, 

 3-5-cleft ; corymbs dense, compound ; rays 4-5, white. 



TANACETUM, L. TAI^rsY. 



Heads many-flowered, discoid, the flowers all fertile ; the 

 marginal ones chiefly pistillate, 3-5-toothed ; scales of 

 the involucre imbricated, dry ; receptacle convex, naked ; 

 achenia angled or ribbed ; pappus a narrow border, or none. 

 — Herbs with alternate dissected leaves, and solitary or 

 corymbose heads of yellow flowers. 



T. YULGARE, L. stem smooth, erect ; leaves bipinnately 

 divided, the lobes serrate; heads corymbose, numerous; 

 pappus 5-lobed. Stem l°-2° high. 



ARTEMISIA, L. Wormwood. 



Heads few or many flowered, discoid ; the central 

 flowers perfect, 5-toothed (sometimes abortive), the mar- 

 ginal ones pistillate, 3-toothed; scales of the involucre im- 

 bricated, mostly with scarious margins ; receptacle convex, 

 naked or villous; achenia obovoid; ^m;ji;j?<5 none. — Aro- 

 matic herbs or shrubs ; leaves alternate, pinnately divided ; 

 heads small, in panicled spikes or racemes. 



A. CAUDATA, Michx. Smooth ; stem slender, branching ; 

 lowest leaves 2-3-pinnately divided, the upper ones pin- 

 nate, with the divisions filiform ; heads globular, in small 

 racemes, forming an elongated panicle; receptacle naked; 

 disTcflowers abortive. 



GNAPHALIUM, L. Eyerlastiitg. 

 Heads many-flowered, discoid, the exterior and pistillate 



