1921] SARGENT, NOTES ON NORTH AMERICAN TREES. XIII 165 



which are found in the Colorado Robinia. 



M 



May 11, 1919, at Fort Bayard in New Mexico 



type station, has the elliptic acute leaflets of the specimen collected by 

 Dr. Thurber, but the short hairs which are mixed through the inflor- 

 escence are nearly destitute of glands. On a specimen of a vigorous 

 shoot collected by A. Rehder (No. 446) in Fresnal Canyon, Sacramento 

 Mountains, New Mexico, on August 20, 191G, the leaflets vary from 

 broad-ovate to oval and are rounded, occasionally acute and distinctly 

 apiculate at apex. In its pubescence this specimen is similar to that of 

 another specimen (No. 389) collected by Rehder a few days earlier at 

 Cloudcroft on the Sacramento Mountains which has the elliptic leaves 

 of the type. Rehder's No. 446, which is probably only an abnormal 

 vigorous shoot of R. neomexicana, agrees in the shape of the leaflets and 

 in their pubescence with the description of R. Rusbyi Wooton & Standley 

 (Contrib. U. S. Nat. Herb. xvi. 140 11913]). Judging by the niaterial 

 I have seen, R. neomexicana is a rare and local plant confined to Grant 

 and probably Socorra Counties in southwestern New Mexico; it appears 



to be always a shrub in habit. 



The plant which has for many years been considered to be Rohinia 

 neomexicana A. Gray (see Sargent's Silva N. Am. iii. 43, t. xiv.) differs 

 from the type in the shape of its leaflets which vary from oval with a 

 rounded apex to oblong-ovate with an acute apex and occasionally to 

 elliptic. It differs also in the stout glandular hairs which cover the in- 

 florescence, the young branches and the fruit. Some of the specimens of 

 this form look very distinct from the type of R. neomexicana, but speci- 

 mens Wke the one collected in May, 1890, by M. E. Jones on the Pinal 

 Mountains, Arizona, with oval leaflets rounded at apex and with the 

 inflorescence and young branchlets nearly destitute of glandular hairs 

 connect the extreme forms, and it does not seem possible to distinguish 

 specifically the two Robinias of the southwestern United States. If this 

 view is accepted the glandular plant becomes Robinia neomexicana var. 

 Inxuriana (Dieck in Gard. Chron. ser. 3, xii. 669 [1892]). This form, 

 which is occasionally a tree from 20-25 feet in height, is widely distributed 

 from the valley of the Cuchura River from ^Yalsenburg to above La Veta, 

 Huerfano County, and of the Purgatory River near Trinidad, Las Animas 

 County, southern Colorado, through New Mexico to the mountain ranges 

 of southern Arizona and northward to southwestern Utah (near Kanab, 



Mt 



Mr. D. M 



become naturalized near Colorado towns in the eastern foothill region 

 as far north as Denver. This variety was introduced by the Arboretum 

 into the gardens of the eastern United States and Europe in 1882 from 

 Colorado, and is probably the only form which has been cultivated as 

 Robinia neomexicana, the plant described by Gray is still unknown in 

 gardens. 



