Tetradymia. COMPOSIT.E. 3 7 'J 



hills and arid plaius, from Los Angeles Co., California, to Arizona; first coll. by Eeermann 

 and by Breu-er. 



189. TETRAD"tMIA, DC. {TerpaSvfjio^, four together, the heads of the 

 principal species only 4-flowered.) — Low and riaid shrubs (of the arid interior 

 of X. Amerie:i), sometimes spinescent, c;inesceiitly tomentose ; with alternate and 

 sometimes faseieled narrow and entire leaves, rather larije cymose or clustered 

 heads of yellow flowers, and a copious white pappus. — Prodr. vi. 540; Deless. 

 Ic. Sel. iv. t. GO ; Torr. et Gray, Fl. ii. -447. 



§ 1. EuTETKADt-MiA. Involucre 4-flowered. of 4 or -5 bracts: pappus ex- 

 tremely copious: akenes either very vilhrns. glaUrate, or glabrous, varying even 

 ill the same species : undershrubs, a foot or two Irigh. 



^^T. canescens, DC. Permanently cauescent with a dense close tomentum, unarmed, l";is- 

 tigiately branclied : leaves from narrowly linear to spatulateJanceolate, an inch or ]c'>s long : 

 heads half to three-fourths inch long, must of them short-peduuculate. — Prodr. 1. c. ; Deless. 

 Ic. iv. t. 60. — Hills and plains, along with Ai-temisiu xridentuta, X. Wyoming and Brit. 

 Columbia to Xew Mexico, Arizona, aud eastern horders of California. J'asses freely into 



Var. inermis, Gray, Bot. Calif, i. 40S. A form witl) shorter and crowded brandies, 

 shorter leaves more iuclined to spatulate and lanceolate, and smaller heads — T. inermis, 

 Kutt. Trans. Am. Phil. !Soc. vii. 415; Torr. & Gray, 1. c. — The commonest aud almost the 

 only form eastward. 



T. glabrata, Guat. "Whitened with looser at length decidiiuus tomeutum, unarmed : 

 brandies more slender, sjireading ; leaves at length naked and greeu, primary ones slender- 

 subulate, cuspidate, on young slioots appressed, half-inch long; those of fa-ciiles in their 

 axils sjiatiilate-linear, fleshy, pointless: heads mostly slmrt-peduuculate : invokicre often 

 glabrate : akenes as far as known very villous. — Pacif. R. Rep. ii. 122, t. 5; Eaton, Bot. 

 King Exp. ins : Gray, But. Calif, i. 40S. — Common in Utah aud to the eastern borders of 

 California and .S. E. Oregon; first coll. by Beckirith. 



T. Nuttallii, Torr. & Gray. PubescriKe and foliage of T. canescens, vai. inermis, bearing 

 rigid divergent spines in place of primai-j leaves : lea^v es of the axillary fascicles mostly 

 spatulate : liea.ls more glomerate. — Fl. 1. c. ; Eaton, 1. u. T. spinosa, Xutt. 1. c, not Hook. 

 & Arn. — Utah aud Wyoming or S. Idaho, yattall, ]Vatso}i. 



§ 2. LiGOTHiMNUS. Torr. & Gray. 1. c. Involucre 5-9-flowereil. of 5 or 6 

 broader bracts : proper pappus less copious, reduced nearly or quite to a single 

 series of bristles, which are covered by a false pappus of the extremely long very 

 soft and white woolly hairs which densely clothe the akene : shrubs 2 to 4 feet 

 hiuh, at least the branches densely white-tomentose. — Lagothmnmis. Xutt. Trans. 

 Am. Phil. Soe. vii. 41(i. 



T. spinosa, Hook, i Arx. Branches divaricate, rigid, bearing rigid and straight or re- 

 curved s]iiiies in jJace of primary leaves : secondary leaves fa-cicled iu their axils, small, 

 fleshy, linear-clavate, glabrous or glabrate: heads scattered, pedunculate, fully half-inch 

 long': pappus of comparatively rigid capillary bristles, somewhat surpassing the wool of the 

 akene. — Bot. Beech. 360; Torr.'^ Gray, 1. c. ; Gray, Bot. Calif. 1. c — Lo'IvIIioiiukis^ micro- 

 phiill,i.<& L. ambigii'is. ymt. Trans. Am. Phil. ^M, . vii. 416. — .•-. Wyoming and Utah to 

 Idaho, E. Oregon, and along the southi-asteru borders of California to border of Arizona. 

 «=«!T. comosa, Ukat. Branches erect, el.'iigated: primary leaves linear, suft, floccose-tomen- 

 tose : the earlier 2 or 3 inches long and 2 lines wide, plane ; those of the branches often fili- 

 form and deciduous, some of the upper changed to long and soft spines : fascided secondary 

 leaves wanting, or fewer and like those of T. spinosa : heads corymbose or glomerate at 

 the summit o/tlie branches : pappus finer and more scanty, concealed by the long wool of 

 the akene.- Proc. Am. Acad. xii. 60; Bot. Calif, ii. 4.5S.— 'X. W. borders of Xevada 

 {Ldiiiih.ii), San Bernardino aud Sau Diego Counties, California, Parri/, Lemmon, Parish, 

 Cleveland. 



