410 Compositaceae 
DD.  Herbage villous-pubescent; heads |—8, 12-16 mm .wide. W. 
T. huronense Nutt. (Seashore Tansy) 
CC. Herbage glabrous or very nearly so; heads many, 6—10 mm. wide. W. 
T. vulgare L. (Garden Tansy) 
Herbs or shrubs, annual or perennial, bitter, aromatic. Leaves alternate. Heads 
rayless, small, many-flowered, paniculate when many, usually nodding; flowers of | or 2 
kinds, white or yellowish; involucre-bracts imbricated in 2 or more series: receptacle naked 
or woolly. Outer flowers sometimes pistillate and inner flowers perfect, or all flowers. 
perfect. Akenes obovate or oblong, usually with a small epigynous disk. Pappus none. 
(Honor of Artemisia, the wife of Mausolus. ) 
A. Shrubs. 
B. Plant spiny; akenes with long cobweb-like hairs. E. 
A. spinescens Eat. (Bud-brush) 
BB. Plant not spiny; akenes without cobweb-like hairs. 
C. Leaves 3—5-cleft or -parted, the lobes linear; 26 dm. high. 
D. Heads usually solitary in the axils of ordinary leaves; panicle spike-like. E. 
A. rigida Gray (Scab-land Sagebrush) 
DD. Heads  clutsered; panicle thyrsoid. E. (A. tripartita. ) 
; A. trifida Nutt. 
CC. Leaves entire to 3-toothed or -lobed, but the lobes not linear: : 
E. Plant 1—3 dm. high; leaves entire to 3—5-lobed, the lobes cuneate, obo- 
vate. E. A. arbuscula Nutt. 
EE. Plant 5—20 dm. high; leaves entire to 3-toothed, the teeth triangular. E. 
(A. tridentata angustifolia.) A. tridentata Nutt. (Common Sagebrush) 
AA. Herbs or merely shrubby at base. 
F. Leaves parted or dissected into oblong or linear segments.. 
G. Leaves glabrous or nearly so. 
H. Leaf-lobes filiform, entire. E. 
A. prescottiana Bess. 
HH. Leaf-lobes wider, laciniate or toothed. E. 
A. biennis Willd. 
GG. Leaves pubescent. 
I. Receptacle woolly. - 
J. Leaves silvery-pubescent, leaf-segments short, filiform. FE. 
A. frigida Willd. (Pasture Sagebrush) 
JJ. Leaves not silvery; leaf-segments oblong or linear-oblong. E. 
A. absinthium L. (Wormwood) 
II. Receptacle not woolly. 
K. | Heads 2—-3 mm. wide! : 
L.. Plants 5-15 em. high. E. A. pedatifida Nutt. 
LLY ~ Plants 30270 emehishiee.: A. canadensis Michx. 
KK. Heads 4—5 mm. wide. W.C. E. (A. borealis wormshioldii.) 
A. borealis Pall. ; 
KKK. Heads 8—10 mm. wide. C. E. (A. saxicola.) 
A. longipedunculata Rud. 
GGG Leaves tomentose: at least on the lower surface. 
M. Involucre glabrous or nearly so. C. E. (A. incompta; A. discolor in- 
compta.) — - A. discolor Doug. 
MM. Involucre densely pubescent or tomentose. 
