CHORIZANTHE. 53 



beaked ; embryo in rather copious albumen, cotyledons yellowish-green, 

 with long radicle. 



Habitat : first discovered by V. Rattan, Placerville ; lately rediscov- 

 ered, 1883, by Mi's. R. M. Austin and C. C. Parry, on volcanic rocks 

 at Chico; also, by Mrs. K. Curran, at Folsom. In its low, prostrate 

 habit, with frequent reddish stems, it is more suggestive of Euphorbia 

 than Polygonum. 



6. C. RiGiDA, Torr. & Gray, Watson, 1. c. Erect, 2-4 inches high, 

 villous-pubescent, shortly branched above, forming dense spinose heads ; 

 radical leaves orbicular-ovate, long petoled, upper cauline leaves usually 

 larger, with broad-ovate orbicular lamina abruptly contracted into a 

 long petiole, white villous-pubescent beneath, appressed pubescent 

 above; branches in the axils of the upper leaves usually densely crowd- 

 ed, or occasionally prolonged; upper involucral bracts in cymose clus- 

 ters, spinescent, becoming rigid, exceeding the involucres; involucres 

 variable in size, villous-hairy externally, broadly triangular, tube short, 

 obconic (i line long), divisions 3, one longer 2% lines long, i line 

 broad, two smaller i ^3 lines long, all sharply costate, the ribs prolonged 

 into stout awns, and with conspicuous marginal nerves and few cross- 

 veins; flowers single, pedicellate, jointed at the base of the perianth, 

 tube slender, obconic; segments equal, ovate-acuminate villous exter- 

 nally ; stamens 9, inserted on the throat, with short filaments, and broad 

 oval anthers; styles short, recurved ; akene broadly triangular, beaked; 

 embryo with rather thick yellowish cotyledons, and blunt radicle. 



Habitat : Gravelly table-land of the Colorado valley, extending east- 

 ward into Southern Utah; in its winter vestiges showing only dense 

 heads of the persistent rigid spinose bracts. 



Group B. Orthosperma. 



Cotvledons ovate or linear, luitli straiglit radicle. 



§3. Chorizanthella. Involucres i flowered, 3-5 cleft, the larger 

 divisions foliaceous, with prominent mid-ribs and marginal nerves, the 

 smaller narrow, all with i-igid recurved tips, and uncinate awns, tube 

 narrowly cylindric, tapering to the base, conspicuously or obscurely 

 corrugated, or smooth and ribbed; flowers pedicellate, included or 

 slightly exsert; stamens 6-9, inserted on the tube, near the middle, or 

 on the throat. 



7. C. CORRUGATA, Torr. & (rray, Watson, 1. c. Erect, 1-3 inches 

 high, flocose-tomentose below, smoother above, densely branched near 



