Pterostegia. POLYGONACE^E. 39 



* * Involucres cylindrical: bracts not foliaceous. 



24. C. corrugata, Torr. & Gray, 1. c. Somewhat villous-pubescent and tomen- 

 tose, much branched from the base and ascending, 2 to 4 inches high : leaves ovate, 

 tomentose beneath, half an inch long, on slender petioles : bracts subulate-setaceous, 

 small : involucres numerous, the tube 1 or 2 lines long, narrow and attenuate at 

 base, scarcely angled, strongly corrugated, bearing 3 foliaceous ovate-lanceolate 

 short-awned and uncinate lobes, somewhat toinentose above and rather longer than 

 the tube : flowers white, included, less than a line long and about equalling the 

 pedicel : segments oblong, equal, villous above : stamens 6 or 9 on the middle of 

 the tube. 



Near Fort Yuma (Gen. Tliomas) and northward in the Colorado Valley, Palmer. 



25. C. Watsoni, Torr. & Gray, 1. c. Villous-pubescent and somewhat tomen- 

 tose, with spreading or procumbent branches, 2 to 4 inches long : leaves narrowly 

 oblanceolate, an inch long or less, tomentose beneath : bracts subulate-setaceous, 

 short or somewhat elongated, rarely foliaceous : involucres clustered or solitary ; 

 tube narrow and scarcely angled, 2 to 2| lines long, obscurely corrugated ; teeth 5, 

 unequal, subulate and uncinate, the larger often foliaceous", 1 to 6 lines long : flower 

 yellow, at length slightly exserted, on a slender pedicel, a line long : segments 

 oblong, acute, slightly villous : stamens 9, at the throat, with very short filaments. 



-Watson, Bot. King Exp. 313, t. 34. 

 On the Mohave River (Palmer) ; Northern Nevada, Torrey, Watson, Lemmon. 



8. LASTARRIJEA, Remy. 



Involucre none. Perianth involucre-like, coriaceous or chartaceous, tubular, 

 5 - 6-cleft to the middle ; the narrow teeth rigid and awned, recurved and uncinate. 

 Stamens 3, inserted on the throat, with a small membranous tooth each side of the 

 very short filament. Akene triangular, glabrous. Embryo curved; the narrow 

 cotyledons longer than the radicle. A small diffusely branching annual, native 

 of Chili, diffusely branched from the base and very fragile, with linear leaves, verti- 

 cillate oblong or lanceolate uncinately awned floral bracts, and flowers sessile in the 

 forks and terminal. 



A single species, with the habit of Euchorizanthe. 



1. L. Chilensis, Remy. Branches procumbent or ascending, 2 to 4 inches long, 

 hirsute : leaves an inch long or less, usually very narrow : lower bracts similar, in 

 whorls of 5 ; the floral ones 1 1 to 3 lines long, concealing the flowers : perianth 1 

 to 1^ lines long, terete and becoming chartaceous at base : styles very short. Gay, 

 Fl. Chil. v. 289, t. 58, fig. 1 ; Meisner in DC. Prodr. xiv. 186 ; Torr. & Gray, 

 Proc. Am. Acad. viii. 199. 



From Contra Costa County to San Diego ; perhaps introduced from Chili by the agency of sheep 

 or cattle. It much resembles some species of Chorizantfic in appearance, and the flowers are so 

 concealed by the bracts that the plant is liable to be overlooked. 



10. PTEROSTEGIA, Fisch. & Meyer. 



Involucre of a single bract, subtending and shorter than the solitary sessile 

 flower, rounded and more or less 2-lobed, at length becoming enlarged, scarious and 

 reticulated, loosely enveloping the akene and gibbously 2-saccate on the back. Peri- 

 anth 6- (rarely 5-) parted ; segments oblong-lanceolate, equal. Stamens inserted at 

 the base of the segments, as many or fewer. Akene triangular, glabrous. Cotyle- 

 dons rounded, accumbent upon the radicle. Very slender weak leafy annuals, 



