160 ZYGOPHYLLACEAE. 
CovitLEA. Creosote Bush. 
(Family Zygophyllaceae). 
Odoriferous small shrubs exud- 
ing balsam where wounded: ever- 
green. Twigs 4-angled, becoming 
round in age, with short inter- 
nodes: pith 4-sided, continuous. 
Buds solitary, sessile, small, ovoid, 
with 2 scales, usually imbedded 
in balsam. Leaf-scars opposite, 
somewhat raised, minute, round: 
bundle-trace 1, usually, like the 
outline of the scar, concealed by 
the exudation: stipules relatively 
large, brown, persistent. Leaves 
short-stalked, of 2 faleate more or 
less parallel leaflets. Fruit, when 
present, long-hairy capsules, 
(Larrea). 
Few plants are more character- 
istic of the dry country than the 
creosote bush or, as it is called 
often though improperly, grease- 
wood, and none is more readily recognized at sight. As in 
lignum vitae, the evident persistent stipules give it a dis- 
tinctive character. In an account of the native trees and 
shrubs published as Bulletin 87 of the New Mexico Agricul- 
tural Experiment Station, Wooton speaks of the characteris- 
tic bright color of Covillea in contrast with the prevailing 
gray of other vegetation. 
Twigs at first green, puberulent. C. tridentata. 
