498 COMPOSITAE (COMPOSITE FAMILY/ 



10. ISOCOMA Nutt. 



Herbaceous or suffrutioose, commonly inore or le^s balsamia- viscid,. Leaves 

 not punctate, sometimes dentate or pinnatifid. Heads several-many-|iowered, 

 bracts of the involucre either coriaceous or firm-chartaceous and usually, some- 

 what herbaceous or thickened at the obtuse or barely acute ap^?f,, all strictly 

 appressed and well imbricated, but the vertical ranks inconspiciiou?. . Styler 

 appendages subulate-lanceolate or broader, shorter thaij the stigmatio portion. 

 Acnenes short, sericeous-pubescent, t'appus of numerous, sordid bristles, the 

 innermost, longest and often distinctly flattened. , , , 



1. Isocoma Wrightii (Gray) Rydb. Bull. Torr. Bot. Club 33; 152. 1906. 

 Commonly glabrous or nearly so; stems rather strict and slender, 3-5 dm. 

 high from a lignescent base; leaves thickish, narrowly linear, entire, some- 

 times lower ones sparingly laciniate-dentate, margins either smooth or spar- 

 ingly hirtello-scabrous: heads 8-10 mm. high, 7-15-flowered, usually numer- 

 ous and crowded in a corymbiform cyme; bracts of the involucre oval-oblong 

 to broadly lanceolate, obtuse'; the back at or near the apex usually greenish, 

 but no definite tip. — Banks of streams and' in saline soil; western Texas to 

 Arizona and in (?) Colorado. 



11. SIDERAHTHUS Eraser 



Annual or perennial herbs or shrubs. Leaves' alternate; blades flat,' 

 spinulose-tpothed or lobed or pinnatifid, commonly sessile. Heads radiate 

 and showy or rarely discoid. Involucres hemispheric or campanulate, many- 

 flowered; bracts in several series, the inner successively larger. Receptacle 

 flat or nearly so, naked, generally pitted. Ray-flowers pistillate; disk- 

 flowers mostly perfect. Corollas yellow; tube scarcely dilated into a throat. 

 Anthers obtuse at the base. Stigmas flattened,' with lanceolate' appendages. 

 Achenes obtuse, pubescent, mostly 8-10-nerved. Pappus of, 1-3 series, of 

 many unequal hair-like bristles, persistent.— -(&iocarpMTO Nutt.) This aiid 

 the following seven genera were all included in the Aplopdppus of the Manual. 



Annuals. • " ' 



Leaves spinescently toothed; stem stout, simple . . . 1. S. annUus. , < 



Leaves pinnatiHd; stem slender, branched . . , . . 2. S. gracilis. 

 Perennials. ,' , ' '■-•'.' 



Leaves spinescently toothed; stems numerous from a woody caudex 3. :S. grindelioides:* 

 Leaves pinnatifid; stems ft'om a woo^y caudex; canescently tomen- , ,^ , 



tose,. cinereous, or glabrate. ■ , , , , ' ' i ^ 



Involucres somewhat glandular; leaves pinnatifid to sub-entii'e ' . 4. S. aus,tralis. 



Involucres not glandiUar; all the leaves pinnatifid . . ' . ■ S. S. spinulosus. 



1. Sideranthus annuus Rydb. Bull. Torr. Bot. Club 31: 653; 1904^,, An- 

 nual, 3-7 dm. high, viscid-glandular and pub,esc,emt or puberulent: jeaves 

 lanceolate or narrowly oblong, incisely pinnatificj or dentate with salient 

 narrow teeth: heads somewhat cymosely paniculate, 10-14 mm. high, usually 

 naked-pedunculate; bracts of the, involucre linear-subulate and with slende^-, 

 spreading green tips: stronger bristles of the fulvous or at fcngth rufous pap- 

 pus numerous: rays golden-yellow. AplopappViS.mbiginosus. — On th(e plains; 

 Kansas and Nebraska to Colorado. , , 



2. Sideranthus gracilis (Nutt.) Rydb. Fl. Col,. 344. 1906., Annual, or her 

 coming lignescent at base and more enduring,, canescently pubescent, oc- 

 casionally glabrate and glandular-scabrous; sterns 1-3 dm. high, mjich 

 branched: leaves linear or the lowest spatulate, pinnatifid, or the upper few- 

 toothed or entire, tipped or also sparsely fringed with long and slepder bris- 

 tles: heads 8-12 mm. high; bracts of the involucre mostly, setaceous-tipped: 

 pappus rigid ; the larger bristles manifestly dilated below. — ^N^w Mexico and 

 Colorado to Utah and Arizona. 



3. Sideranthus grindelioides (Nutt.) Brit. Man. 932. 1901. Perennial 

 by a deep woody root, finely pubescent; stems tufted, simple, erect, 1-3 dm. 

 high: leaves oblong-lanceolate to spatulate, sessile, or the lower petioled, 



