•^4 I'OLYGUNACK.E. Chorizduthe. 



Bracts more or less foliaceous : flowers 1 J lines long or more. 

 Leaves narrow, not tomentose : teeth long-divergent : lobes 



undulate, uneciuai, oblong-ovate, aeiitish. 17. C Pakkyi. 



Leaves and bracts ovate-oblong, small, tomentose beneath : 

 involucres tomentose, inditt'usecj'mes : flowers 2^ lines 

 long ; lobes narrow, very uneiiual : stamens often 6. 18. (\ Xanii. 

 Leaves and oblanceolate bracts tomentose Ijeneatli : involucres 

 more glabrous, in smuU cymes ; teeth short : flowers 

 l.\ lines long ; lobes broadly oblong : stamens 6. 

 Villous-fiubescent : one tooth long-awncd : flowers yellow, 



uiUHiually deft : stamens 3 or !). 

 Pubenilent, thirkjointed : involucres narrow ; teeth very 

 sliort : lobes narrow, nearly ecjual : stamens 3 or (5. 

 Villous-pubescent : bracts distinct : involucres 3-5-tootlied, 1-flowered ; 

 flowei-s t3-clcft : stamens 6 or 9, on the throat. 

 Involucres broadly triangular: bracts foliaceous. 



Leaves and bracts narrow ; floral bi-acts very sliort : teeth broad. 

 Leaves and bracts ovate, tomento.se beneath : floral bracts elongated, 

 stout, ligid and persistent : teeth 3, lanceolate. 

 Involucres narrowly cylindrical : bracts not foliaceous. 

 Leaves ovate ; involucres strongly corrugated, 3-toothed. 

 Leaves narrow ; involucres obscurely corrugated, .')-toothed. 



§ 1. Involucres coriaceo-chartaceous, the awns of the erect or divergent teeth not 

 uncinate: Jioivers on slender pedirels, included or more or less exserted, 

 white or 2^tnkish: ]jeria7ith 6-jjarted, 2'idH-srent icifh soft hairs, the i) 

 stamens inserted upon the base: hractlets minute. Glabrous or f/landular, 

 never villaus-toinentose : bracts ternate, foliaceous, more or less connate and 

 unilateral: leaves all radical and spat ul ate : involucres axillari/ and 

 terminal in open dichotomous panicles. — Muchonea. 



* Involucres 1 - S-flotcerecf, with 3 to 6 mostli/ erect teeth, and with 3 to 6 divari- 

 cate cuspidate or uwned spurs at base: bracts small. — [Centrosteyia, Gray.) 



1. C. Thurberi, AVatsoii. IMore or less ;^'lamlular-pviberulunt, G inches high or 

 usually less, braiirliing iVoin near the ]>a.se : leaves an ineli long, glahrons, slightly 

 ciliate: Imiets (d)lung, more or les.s united, 1 to 3 lines long: involucres glal>ron.s, 

 chartaceous, triangiilur-prisniatic, ohscnrely reticnlated, 2 or 3 lines long and \ to 1 

 line broad, with 3 hroad straight-awned spurs at base, and with 3 to 5 l)road and 

 short erect teeth : flowers 1 or 2, rarely exseiled, nearly a line long, pul)escent at 

 hase : segments oblong-spatulate, obtuse or emarginate, the alternate ones slightly 

 shorter. — Proc. Am. Acad. xii. 209. Centrostef/ia Thurberi, Gray; Benth. in DC. 

 Prodr. xiv. 27 ; Torr. & Gray, 1. c. 192. 



In the desert region of S. California and eastward, from Fort Tejon (Ruthruck), Sau Bernardino 

 (Parry) and San Felipe {T/iurbcr) to Southern Utah. 



2. C. leptoceras, AVatson, 1. c. Very slender, nearly glahrous : leaves and bracts 

 as in the last : involucres 2 or 3 lines long, somewhat hii-sute, deeply 4 - G-cleft, the 

 coriaceous turbinate base surrounded by as many rigid usually uncinate awn-like 

 spurs ; lobes rigid, narrow, unequal, attenuate into straight rigid somewhat divergent 

 awns : flowers 2 or 3, occasionally exserted, villous-])ubescent, half a line long : 

 .segments narrowly oblong to ovate, nearly equal. — Cevtrosteyia leptoceras, Gray; 

 Torr. & Gray, 1. c. 



Plains of San Gabriel (Lobb) ; near San Beinardino, not rare, Pdrri/. 



* * Involucres '[-flowered, with 2 to 5 unequal stout diverf/ent teeth, not spurred 

 at base: bracts consjiicuous. — (§ Mucronea, Torr. & Gray.) 



3. C. perfoliata, Gray. S))aringly hirsute and glandular, a foot high or less, 

 often bright r.;d : leaves an inch or two long : bracts connate about the stem, form- 

 in" a somewhat unilatrrul triangtdar reticulated ilisk, tlie lower often an inch broad :. 



