LEGUMINOSAE. 135 
Prosopis. Mesquite. 
(Family Leguminosae). 
Shrubs or small trees. Twigs 
moderate, zig-zag: pith minute, 
angular, continuous. Buds mi- 
nute, rather quickly developing 
into stout spurs bristling with 
stipules and frequently flanked 
by a solitary spine or mostly a 
pair of terete nearly straight 
spines, the end-bud lacking. Leaf- 
sears alternate, often 2-ranked, 
somewhat raised, rounded or el- 
liptical: bundle-traces 3: stipules 
long persistent. Leaves of 2 pin- 
nate leaflets terminating the pet- 
iole, or of 4 such leafiets. (In- 
cludes Strombocarpa). 
Notwithstanding its compound 
leaves, their characteristic droop- . 
ing position and the openly 
- branched top of the tree cause a 
grove of mesquite to suggest a 
peach orchard to many people when they see it for the first 
time. As in many other Leguminosae the stipules of Prosopis 
persist, even when they are not converted into spines; and 
their presence gives a peculiar shaggy appearance to the axil- 
lary spurs on which the foliage is clustered. 
The screw-bean or tornillo, P. pubescens, is separated 
frequently from the other species under the generic name 
Strombocarpa. 
1. Stipules becoming spines: downy. (1). P. pubescens. 
Spines not representing the nodal stipules. 2. 
2. Glabrous. (Common mesquite). (2). P. glandulosa. 
Leaves, and twigs above, gray-pubescent. P. velutina. 
