214 RHAMNACEAE. 
COLLETIA. 
(Family Rhamnaceae). 
Shrubs, horridly spiny by the 
decussate branchlets: pith moder- 
ate, rounded, white, continuous. 
Buds superposed, the upper at 
once developing into a_ spine- 
branch, the lower minute with 
about, 2 scales concealed in _ to- 
mentum. Leaf-scars lacking, the 
opposite minute scales which rep- 
resent the true foliage persistent. 
Except for a few other species 
of Colletia, which have slenderer 
or more rounded spines and are 
seldom if ever seen in this coun- 
try, Colletia cruciata, or C. hor- 
rida as it is called sometimes, re- 
sembles only the related genus 
Adolphia of the Southwest, and 
the rather distantly related Mexi- 
can Koeberlinia which differs 
from both in having its spines 
alternately placed and not in the form of a cross. 
Gray-tomentulose, leaf-green when denuded. C. cruciata. 
