COMPOSITAE (composite FAMILY) 5.11 



long, narrowly oblong-lanceolate or linear: involucre 10-14 mni.i broad, the 

 bracts apute, somejvhat ciliate : rays white, about 12 mm. long. Aster Xylorhiza. 

 — Naked clayey saline soils; south-central Wyoming. 



Id. Xylorhiza glabriuscula villosa (Nutt.) A. Nels. Intermediate between 

 the prece(Jjng and the following species: softly villous or toment'ose. {X. 

 villosa Nutt. 1. c. 298.) — Habitat and range of the species. 



2.., Xylorhiza Parryi Gray, Am. Nat. 8: 212. 1874. Somewhat hoary with 

 a thiri; loose, villous tomentum; stems several from the woody crowns, 1-2 dm. 

 high: leaves spatulate4ineai:i cuspidate, -3-5 cm. long: peduncles solitary: 

 involucral bracts oblong-lanceolate, long-acuminate, cinereous-pubescent : rays 

 mmierous, white, 10-14 mm. long: achenes white-yillous. Aster Parryi. — 

 In denuded or saline soils; western Wyoming, Colorado, and adjacent Utah. 



3. Xylorhiza venusta (Jones) Heller, Cat. N. A. PlantS"8. 1900. Softly' 

 villous-tomentose up to the canescent inyolucre; stems riiany. erect, stout, 

 simple, shrubby at base: leaves all entire, oblanoeolate or lowest spatulate, 

 scarcely petioled, 5-8 cm. long, generally apiculate, larger ones indistinctly 

 3-nS-A^ed: peduncles monocephalous, 1-2 dm. long: in'ir'olticral bracts. oblong- 

 ovate and abruptly long-acuminate, in about 3 series: rays white or light 

 purple, linear-oblanceolatej 20^25 mm. long: pappus of unequal, stiff bristles; 

 achene silky.— Western Colorado to Utah. 



22. ASTER t!' AsTEK 



Perennial or rarely annual herbs, with alternate entire or serrate leaves 

 and racemose, paniculate, or corjrmbose (rarely solitary) heads of flowers with 

 white, purple, or blue ray, and yellow (often changing to purple) disk corollas. 

 Heads many-flowered; the ray-flowers in a single series, not very numerous, 

 pistillate; thope/ of the disk tubular, perfect. Bracts of tlie involucre more 

 or less imbricated, msually with herbaceous or foliaceous tips. Receptacle 

 flat or convex, naked. Appendages of the style (in the disk-flowers) lanceo- 

 late or subulate, acute. Pappu^ pimple; of numerous, often unequal, scabrous 

 capillaryi bristles.', Achenes usually compressed. — (Includes Brachyactis 

 Ledeb., Eiicephalus Nutt.y and Vnamia Greene.): 



.,.r ,;,: .;; . ANNUALS (BrocAi/acfis Ledeb.) 



Involucral bracts linear, acute . " . . . . . 1. A. angustus. 



Involucral bracts oblong, obtuse . . . . . . . 2. A. frondosus. 



PERENNIALS iEucephalus Nutt.) 



INVOLUCRAL BRACTS' WITH PROMINENT OR KEELED MIDRIB, DRY AND CHARTACEOVS, 



U^UAt-LY PURPLE-TIPPED ' ' 



Stems mostly .simple below: the involucral bracts acute. 



Stout, iisea{IIy°6-15 dm. high; heads large (12-15 mm. high) ; 3. A. Engelmaimii, 

 Slender; 3-6 dm. high; h^ds smaller, with conspicuously 



purple-tipped bral©ts'* ■'. ,- . . . , '■ . 4. A elegans. 

 Stems-mostly branched throughout; at least the outer involucral 



bracts obtuse , , . "'i^- .'■:'. . . . ^.',5. A. glaucus. 



■ PERENNIALS 



INVOLUCRAL BRACT& NEITHER KEELED NOR WITH PROMINENT MIDRIB, 

 AT LEAST THE TIPS GREEN 



Stems low, usually less than 1 dm. high, monocephalous; high 

 alpine. , ■ ' • 

 From a low woody crown or caudex. ,■ ._, ; 



Stems and involucre lanate-pubescent . . . , ... .6. A. culminis. 

 StemB;»!id involucre minutely glandular '. , . . . 7. A. Kinpii. 

 From filiform creeping rootstocks ..... ,.,.-, ., 8. A. andmus. 

 Stems taller, usually more than 1 dm. high, bearing solitary, 

 few, or many heads, mostlyj from. rootstpoiis which are pften 

 branching and matted or tufted. " . . 'i - < -. 



Pedunolesaad involucres glandular. 



Stems simple, rarely branching at summit. 



Meads solitary or raoemed . , . , . . 15. A. campestrift- 



eads not in racemes. 



