368 COMPOSITiE. Artemisia. 



§ 1. Deacuxcdlus, Bess. — Heads heterogamous ; the disk-flowers hermaphro- 

 dite but sterile, their ovary abortive, and style mostly entire, peltate-penicillate 

 at tip : receptacle not hairy. — Oligosporus, Cass. 



# Akenes and flowers beset with long cobwebby and crisped hairs : spinescent undershrub. — 

 Picrothamnus, Nutt. 



A. spinesoens, Eaton. Stout and densely branched, rigid, 4 to 18 inches high, villous- 

 tomentose : leaves small, pedately 5-parted and the divisions 3-lobed ; lobes spatulate : heads 

 globose, raceraosely glomerate on short and leafy branclilets, which persist as slender spines : 

 bracts of the involucre 5 or 6, broadly obovate : female flowers 1 to 4 ; hermaphrodite-sterile 

 flowers 4 to 8, their corolla ventricose-campanulate from a, narrow base. — Bot. King E.\p. 

 180, t. 19, f. 15-21 ; Gray, Bot, Calif, i. 404. Picrothamnus desertorum, Nutt. Trans. Am. 

 Phil. Soc. n. ser. vii. 417; Torr. & Gray, Fl. ii. 289. — Wliole desert region of Wyoming, 

 t'tah, Nevada, and Idaho, reaching the borders of California; first coU. by Douglas (incom- 

 plete specimens), then Nuttall. 



* * Akenes nearly glabrous : receptacle except in last species hemispherical or ovate : no spines. 



-1— Biennial herb ; leaves all filiform. 

 ' A. caudata, Michx. Glabrous, with one or more strict stems, 2 to 6 feet high : leaves 1-3- 

 pinnately divided into slender filiform lobes : heads small (a line in diameter), very numer- 

 ous in an ample elongated thyrsus. — Fl. ii. 129 ; Nutt. Gen. ii. 144; Torr. & Gray, Fl. ii. 

 417. — Sandy ground, Canada to Texas near the coast, Illinois to Saskatchewan and Kansas. 



^— -1— Perennial herbs, the last two or three species sometimes frutescent at base : heads many- 

 flowered. 



++ Leaves dissected. 



A. Canadensis, Michx. A foot or two high from a perennial (or sometimes biennial'?) 

 root : glabrous or mostly with at least the radical and sometimes all the leaves either sparsely 

 or canescently silky-pubescent : leaves mostly 2-pinnately divided into narrow linear or 

 almost filiform but plane lobes, of thickish texture : heads 1 or 2 lines long, very numerous 

 in a compound oblong or pyramidal virgate panicle (in reduced specimens northward fewer 

 in a simple panicle) : involucre greenish, glabrous or rarely pubescent. — Fl. ii. 129 (north- 

 ern form with heads 2 lines broad) ; Nutt. 1. c. ; Torr. & Gray, 1. c. ; Besser, Dracunc. 90, & 

 DC. 1. c, partly (mixed with A, caudata). A, peucedanifolia, Juss. Herb.; Besser, 1. c. 29 

 (A. Canadensis ferula ceo; folio, Vaill.), spec. Herb. Tourn., DC. 1. c. 99, excl. pi. Mitch. 

 A. campestris, Pursh, Fl. ii. 521 1 excl. syn. ; Richards. App. Frankl. Journ. A. desertorum, 

 in part, Bess, in Hook. Fl. A. commutata, Bess. Dracunc. 68, & in DC. Prodr. vi. 98. A. 

 Parjfica, Nutt. Trans. Am. Phil. Soc. 1. c. 399 ? — Rocky banks and plains, N. New England 

 to Hudson's Bay, west to the Pacific in Washington Terr., and south in the Rocky Mountain 

 region to New Mexico, Utah, and Arizona. {N. W. Asia.) 

 "A. borealis, Pall, a span or two high from a stout caudex : stems simple : leaves silky- 

 pubescent or silky-villous ; radical and lower 1-2-ternately or pinnately divided into linear 

 lobes ; uppermost linear and entire or 3-parted : heads (2 lines broad) comparatively few, 

 crowded in a narrow (rarely compound) spiciform thyrsus with leaves interspersed: invo- 

 lucre pilose or glabrate, pale-fuscous to brownish. — It. iii. 129, t. hh, f. 1 ; Bess. Dracunc. 

 78, & in DC. 1. c. 98; Torr. & Gray, 1. c. A. spithamaa, Pursh, Fl. ii. 522. A. ciolacea, 

 Ledeb. Ic. Fl. Alt. t. 475. —Arctic America, Labrador to Alaska, and Rocky Jlountains to 

 Colorado in the alpine region. (Greenland, N. Asia.) 



Var. Wormskioldii, Bess. Taller, 10 to 16 inches high, with more numerous heads 

 in looser or compound narrower thyrsus. — Dracunc. 83, & Hook. 1. c. .327. A. Grmitandica, 

 Wormsk. Fl. Dan. 1. 1585, small specimen. — Hudson's Bay and mountains of Lower Canada 

 (where it seemingly passes into .1. Canadensis, in coll. Allen) to Washington Terr, and N. 

 Alaska. (Greenland, N. E. Asia.) 



A. pedatiflda, Nutt. Cespitose, with a stout lignescent caudex, very dwarf, canescent 

 throughout with a fine and close pubescence: leaves chiefly crowded in radical tufts and on 

 the base of the (inch or two high) rather naked flowering stems, once or twice 3-parted into 

 narrowly spatnlate or nearly linear obtuse entire divisions; heads (hardly 2 lines broad) 

 few, loosely spicately or racemosely disposed, canescently pubescent : heads 12-15-flowered; 

 the hermaphrodite-sterile flowers with stylo barely 2-lobed at summit and no ovary. — Trans! 



