16 SILVA OF NORTH AMERICA. LEGUMINOSAE. 
valleys of southern Arizona and Sonora,! where it often attains the height of fifty feet, with a 
trunk two feet in diameter covered with rough dark brown bark, and with heavy irregularly arranged 
usually crooked branches. This form grows to a larger size than any of the other Mesquites in the 
United States. The leaves are five or six inches long, often fascicled and cinereo-pubescent, with 
short petioles and from twelve to twenty-two pairs of oblong or linear-oblong obtuse or acute pale 
green leaflets from one quarter to one half of an inch in length, and with densely flowered spikes of 
flowers two or three inches long. The calyx is villose.’ 
1 From Nogales to Guaymas, Rose, January, 1897 (No. 1296); ? The earliest specimen of this pubescent form was collected by 
Guaymas, Rose, June, 1897 (No. 1296); El Grupo, Dr. W. J. Dr. George Thurber (No. 667) on the Gila River, and is preserved 
McGee, December, 1896. in the Gray Herbarium. 
EXPLANATION OF THE PLATE. 
PrateE DCXXVIII. Prosopis sULIFLORA, var. VELUTINA. 
. A flowering branch, natural size. 
. A flower, enlarged. 
. A pistil, enlarged. 
A stamen, enlarged. 
. A fruiting branch, natural size. 
. Vertical section of a portion of a legume, natural size. 
. Vertical section of a seed, enlarged. 
. An embryo, enlarged. 
ONO oT FP wwe 
