(J8 MISSOURI BOTANICAL GARDEN. 



In speaking of Y. rupicola and what he called its 

 variety rigida, Dr. Engelmann* refers to intermediate 

 specimens collected by Wright in " Eastern New Mexico " 

 (no. 1909). The leaves of this number in the Torrey 

 herbarium (Plate 37), it is true, are very hard to distinguish 

 from narrower herbarium leaves of Y. rigida, but the cor- 

 responding sheet in the Gray herbarium (Plate 38} clearly 

 represents a crown of the acaulescent Y. rupicola with 

 inner leaves, narrower and less twisted than the outer 

 leaves probably were. A similar intermediate specimen in 

 the Engelmann herbarium, collected by Wright in April or 

 May 1850, on " Hills of the Blanco " is from the region of 

 and accompanied by unmistakable, though detached, leaves 

 of Y. rupicola j to which I should refer all of these speci- 

 mens. 



22. Capsule attenuate-beaked, with round-backed valves. 



Y. rostrata Engelmann, in herb. 



Of the aspect of T. radiosa. Caulescent, at length 3 m. high, simple 

 or short-branched at the crown. Leaves very numerous, rigidly diver- 

 gent, scarcely 10 mm. wide, a little glaucous, flat or biconvex, striate, 

 thin, very pungent, the yellow margin minutely denticulate. Inflores- 

 cence ample, with subincluded base or mostly exserted, glabrous. Flowers 

 white, umbonate at base : style white, attenuate. Capsule oblong-ovoid, 

 thick-walled, with convex valves long-attenuate and spreading above: 

 seeds rather dull, 4 to 5X 6 to 7 mm. Plates 36, f. 2. 40-42. 84, f. 3. 



Northern Mexico, from northern Chihuahua to the 

 Sabinas valley in eastern Coahuila. Plate 93, f. 2. 



In 1852, Dr. Bigelow, of the boundary survey, collected 

 a Yucca with narrow denticulate leaves, somewhat resem- 

 bling ]T. rigida, at Bufatillo, said to be in a volcanic moun- 

 tainous region near Presidio del Norte, and what may pos- 

 sibly have been the same thing on sand hills thirty miles 

 below San Elizario, both along the Rio Grande, and 

 on gravelly hills at Los Moros. In August, 1880, Dr. 

 Edward Palmer collected leaves, capsules, and seeds of ap- 



* Trans. Acad Sci. St. Louis. 3 : 50. 



