364 COMPOSIT © TANACETUM 
ARTEMISIA 
corymbiform cyme, 2-4 lines broad, depressed-hemispheric: marginal 
corollas inconspicuous, terete, with oblique 3-toothed limb. Roadsides and 
waste places. Escaped from gardens, . 
T. Huronense Nutt. Gen. ii, 141. Villous when young, sometimes 
glabrate: stems 1-2 feet high, from long running rootstocks: leaves lanceo- 
late in outline, 2-8 inches long, twice or thrice pinnately divided into lin- 
ear or oblong divisions: heads large, the disk convex, 4-6 lines broad; 
marginal corollas with flattish tube and 3-5-lobed limb, which often ex- 
pands into a cuneate ligule. On sand banks along the coast, Alaska to 
California, the great Lakes and the coast of Maine to Hudson Bay. 
§ 2 Low perennials. Stems,.slender, more naked above, bear- 
ing rather small globular heads. Leaves less dissected, or entire. 
Receptacle convex or conical. Achenes usually utricular, with- 
out pappus. 
T. potentilloides Gray Proc. Am. Acad. ix, 204. Silvery-sericeous: 
stems decumbent or ascending, 4-12 inches long, herbaceous to the ground, 
the naked summit bearing a few slender-peduncled heads: radical leaves 
numerous, petioled, 1-3 inches long, bipinnately or tripinnately parted 
into rather few mostly linear lobes; cauline leaves few, sessile, more sim- 
ple: heads 3-4 lines in diameter, in small paniculate corymbs; bracts of 
the involucre roundish-ovate or obovate: receptacle densely fimbrillate- 
hirsute. Alkaline plains southeastern Oregon to Nevada and California 
T. canum Eaton Bot. King 179, t. 19 f. 8-14. Silvery with minute close 
tomentum : stems erect froma shrubby base, 6-12 inches high, leafy to the 
top: leaves sessile, 6-12 lines long, spatulate and entire, or some of them 
cuneate and 2-3-lobed: heads 2 lines in diameter, congested in small ter- 
minal clusters: involucre cup-shaped, of about 12 ovate scarious-margined 
concave bracts in 2 rows: receptacle conical, not hirsute. On cliffs and 
rocky hills, southeastern Oregon to Nevada and California. 4 
77 ARTEMISIA Tourn. L. Gen. n. 945. 
Bitter aromatic herbs or shrubs with alternate leaves and small 
paniculately disposed commonly nodding heads of yellow or 
whitish flowers. Heads few to many-flowered, small, wholly dis- 
coid; heterogamous the pistillate flowers with small and slender 
tubular corolla, and the hermaphrodite either sterile or fertile; 
or homogamous with the flowers all hermaphrodite and fertile. 
Involucre imbricated in few or several rows. Anthers commonly 
tipped with subulate-acuminate appendages. Achenes obovate 
or oblong, mostly with small epigynous disk and no pappus. 
§ 1 Dracuncuus Besser Bull. Soc. Nat. Mose. viii, 97. Heads 
heterogamous; the disk-flowers hermaphrodite but sterile, their 
styles mostly entire and peltate-penicillate at tip. Receptacle 
not hairy. 
* Achenes and flowers beset with long cobweby crisp hairs; spines- 
cent undershrub. 
A. spinescens Eaton Bot. King, 180, t. 19, f. 15-21. Stems stout and 
densely branched, rigid 4-18 inches high, white-tomentose : leaves 2-4 lines 
long, pedately 3-5-parted, the divisions 3-lobed: heads globose, racemosely 
glomerate on short and leafy branchlets which become slender persistent 
spines: bracts of the involucre 5-6, broadly obovate, obtuse : pistillate flow- 
