$64 COMPOSITE 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. A cad. 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, bipiunately or tripinnately parted 

 into rather few mostly linear lobes; cauiine 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. can urn Eaton Bot. King 179, t. 19 f. 8-14. Silvery with minute close 

 tomentum : stems erect from a 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. 



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 horriogamous 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 DRACUNCULUS Besser Bull. Soc. Nat. Mosc. 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- 



