200 



COMPOSITE. (COMPOSITE FA^ULY.) 



ions 3-lobed ; lobes spatulate : heads globose, racemosely glomerate ou short 

 and leafy branchlets, 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. — Bot. King Exp. ISO. Whole desert region of Wyoming, Utah, 

 Nevada, and Idaho. 



* * Akenes nearly glabrous : no spines. 

 +- Leaves dissected. 



2. A. Canadensis, Michx. A foot or two high: glabrous or mostly with 

 at least the radical and sometimes all the leaves either sparsely or canesceutlv 

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

 filiform but plane lobes, of thickish texture : heads 1 or 2 lines iong, very nu- 

 merous in a compound oblong or pyramidal virgate panicle: involucre greenish, 

 glabrous or rarely pubescent. — Across the continent to the north, and extend- 

 ing southward in the Rocky Mountain region to Xew Mexico and Arizona. 



3. A. borealis, Pall. A span or two high from a stout caudex : stems 

 simple: leaves silky -pubescent or silky-villous ; radical and lower 1 to 2-ternately 

 or pinnate! y 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 : involucre pilose or glabrate, pale- 

 fuscous to brownish. — In the alpine region of Colorado, and far northward 

 across the continent. 



4. A. pedatifida, Xutt. Cespitose, with a stout lignescent caudex, very 

 dwarf canescent throughout with a fine and close pubescence : haves 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 spatulate or nearly linear 

 obtuse entire divisions: heads (hardly 2 lines broad) few, loosely spicately or 

 racemosely disposed, canesceutlv pubescent. — Dry ground, in the mountains 

 of Wyoming, Montana, and Idaho. 



■+- «- Leaves entire or 3-cleft or -parted: the ichole plant or at least the base some- 



ichat woody. 



5. A. draounculoides, Pursh. Glabrous: stems 2 to 4 feet high, either 

 virgately or paniculately branched : leaves mostly entire, narrowly or sometimes 

 more broadly linear, some 3-cleft : heads very numerous in a compound and 

 crowded or open and diffuse panicle, many-flowered. — On plains, from Sas- 

 katchewan to Texas, and westward across the continent. 



6. A. filifolia, Torr. Minutely canescent, even to the 3 to ^-flowered invo- 

 lucre, 1 to 3 feet high, with virgate rigid branches, very leafy : leaves all slender 

 filiform, commonly 3-parted : the upper and those in axillary fascicles entire: 

 heads very small, crowded in an elongated leafy panicle. — Ann. Lye. X. Y. ii. 

 211. Plains, from Nebraska ro Xew Mexico and W. Texas. 



§ 2. Reads heterogamous ; the disk-flowers hermaphrodite and fertile, icith %-cleft 

 style. — Ecartemisia. Ours have the akenes obovoid or oblong and wholly 

 destitute of pappus. 



* Receptacle beset ivith long icoolly hairs. 



7. A. SCOpulorum, Gray. Herbaceous, a span or two high from a stout 

 multicipital caudex, silky-canescent : stems simple, bearing 3 to 12 spicately oi 

 racemosely disposed hemispherical (rarely solitary) heads . radical and few hirer 



