OF ARTS AND SCIENCES. 2Qd 



94. E. Plumatella, Dur. & Hilg. Low, grayish tomentose 

 throughout: intrioately much-branclied from the base, leaves rounded: 

 involucres i line long or less: flowers | to at length 11 lines long, 

 the sepals broadly cuiieate-obovate and refuse. — N. W. Nevada to 

 S. California. 



95. E. IXTRICATUM, Benth. Leaves rounded and viscid-pubescent : 

 panicle diffuse with numerous short divaricate branchlets, glabrous or 

 glabrate : involucres very small, glabrous: flowers minute, sparingly 

 pubescent. — Lower California. 



CHORIZANTHE, R. Br. A polymorphous genus, with which 

 it seems necessary to unite Centrostegia as too closely related to the 

 section Mucronea to be kept distinct. The character upon which that 

 genus mainly rested, the spurs at the base of the involucre, is of fre- 

 quent occurrence in the Chilian Chorizanthe commissuralis, which is 

 without doubt a true Chorizanthe. Moreover, the involucres and spurs 

 in the two recognized species of Centrostegia are very different in char- 

 acter, and in some of the 3Iucronea species the angles of the involucres 

 are frequently rather strongly gibbous at base, showing a tendency 

 towards a like peculiarity. The known species, excepting the peren- 

 nials of Chili, are the following : — 



§ 1. Glabrous or glandular, not villous or tomentose, with radical spatulate 

 leaves and ternate foliaceous more or less connate bracts : involucres in open 

 dichotomous panicles, coriaceo chartaceous, the awns not uncinate : flowers 

 6-parted, soft-pubescent, on slender pedicels : stamens 9, inserted at the 

 base. — Mucronea. S.California. 



* Involucres 1-3 flowered, with 3 to 6 mostly erect teeth and 3 to 6 divaricate 

 cuspidate or awned spurs at base: bracts small. — (Centrostegia, Gray.) 



L C. Thdrbkri. Involucres chartaceous and triangular, with 3 to 5 

 broad short teeth, and 3 broad straight spurs. — Centrostegia Thurbert, 

 Gray. 



2. C. LEPTOCERAS. Livolucres coriaceous, deeply 4-6-cleft, the 

 lobes rigid and attenuate, and with as many rigid usually uncinate awn- 

 like spurs. — Centrostegia leptoceras, Gray. 



* * Involucres l-flowered, with 2 to 5 stout divergent teeth, not spurred : 

 bracts conspicuous. — ( Mucronea, Benth. § Mucronea, Torr. & Gray. ) 



3. C. PERFOLIATA, Gray. Sparingly glandular-hirsute: bracts per- 

 foliate : involucres scattered : sepals laciniate. 



4. C. Califorxica, Gray. More hirsute : bracts unilateral : in- 

 volucres often cl^astered: sepals entire. 



