GOMPOSITAE. 381 



mm. high, terminating short stout peduncles; involucre saucer-shaped, the 

 tegules oblong, obtuse, green, with scarious margins; ray-flowers none; disk- 

 flowers yellowish-green; receptacle conical; akenes oblong; pappus represented 

 by a low sometimes 1-2-toothed crown. 

 Dry ground, very common. 



531. COTULA. 



Annual or perennial strong-scented low herbs with alternate 

 lobed or dissected leaves and slender-peduncled rayless heads 

 with two kinds of flowers; heads many-flowered, hemispheric to 

 globose-; involucre of about 2 ranks of tegules; receptacle flat or 

 convex, naked; outer one or two rows of flowers pistillate, apeta- 

 lous or nearly so; disk flowers tubular, 4-toothed, fertile; mature 

 akenes raised on short erect persistent stalks; pappus none. 



Glabrous; leaves entire to pinnatifid. C. coronopifolia. 



Pubescent; leaves bipinnately dissected. C. australis. 



Cotula coronopifolia L. Glabrous or nearly so, somewhat fleshy; stems 

 decumbent or ascending, 20-30 cm. long; leaves linear-oblong, pinnately in- 

 cised or the upper entire, clasping and sheathing at base; heads subglobose, 

 peduncled, 8-10 mm. broad; pistillate flowers in a single marginal row, their 

 akenes with thick spongy wings. 



Common especially in marshes along the seashore; a native of South Africa. 



_ Cotula australis Hook. Somewhat pubescent; stems slender, much branched, 

 15-30 cm. high; leaves bipinnately parted, the ultimate segments linear; 

 heads small, 4-6 mm. broad; pistillate flowers in 2 or 3 rows, their akenes 

 pedicelled. 



Vancouver Island to California, sparingly introduced; a native of Australia. 



532. TANACETUM. Tansy. 



Perennial bitter strong-scented herbs with alternate pinnately 

 dissected leaves and corymbed heads of yellow flowers; heads 

 many-flowered; involucre hemispheric; tegules imbricated, char- 

 taceous; receptacle naked, convex; flowers all fertile, the outer 

 ones pistillate with tubular 3-5-toothed corollas; akenes angled 

 or ribbed, truncate at top; pappus a short crown. 



Tanacetum huronense Nutt. Soft hairy or woolly, especially in young 

 plants; stems stout, 30-90 cm. high; leaves twice to thrice pinnately dissected, 

 the ultimate segments oblong and crowded; heads 1-2 cm. broad, on stout 

 peduncles; corollas of the pistillate flower flattened, somewhat ray-like, 3-5- 

 cleft; pappus teeth present. 



On sand dunes along the ocean coast. 



533. ARTEMISIA. Sagebrush. Wormwood. 



Herbs or undershrubs, bitter and odorous; leaves alternate, 

 usually dissected; heads numerous, small, in racemes or panicles, 

 several to many-flowered, discoid; flowers yellow, yellowish or 

 brownish, all tubular, the outermost series pistillate or all alike, the 

 more numerous perfect flowers either fertile or sterile; tegules dry, 



