The spines of Fouquieria * 
WINIFRED J. ROBINSON 
The six species now comprised in the genus Fouguieria occupy 
collectively a region extending from the vicinity of the City of 
Mexico northward into California, Arizona, New Mexico and 
Texas. Nearly all of the species find their habitat in arid districts, 
and the localities from which they have been reported may be 
comprised within the southern extensions of the Chihuahuan and 
Sonoran deserts. Among other adaptations, the various species 
exhibit a capacity for casting off the leaves during seasons of 
drought, more or less irrespective of the time of the year, while 
some interesting features of the formation and casting away of the 
bark have been noticed. 
All of the species bear strong spines and seem to be included 
under the single colloquial name “ocotillo” by the Mexicans, 
who use the living plants for hedges and sometimes erect barriers 
by thrusting the ends of heavy branches into the ground in rows. 
Messrs. Coville and MacDougal report having seen shrubs of 
Fouquieria splendens planted within a few inches of young shade 
trees in the streets of Alamogordo, New Mexico. The spreading 
spiny branches were held in a cylindrical clump around the trunk 
of the tree by means of wire and formed a most effective pro- 
tection against damage by animals. 
During the course of some recent work upon this genus, Mr. 
G. V. Nash called my attention to the unusual manner in which the 
spines were formed, which he described as ‘“‘ developed within the 
petivles of the leaves on the new growth, becoming apparent when 
these fall.” + The general anatomical facts presented seemed of 
sufficient interest to warrant a detailed examination, and the results 
of my observations upon Fouguieria splendens and F. Macdougalit, 
Specimens of which are growing in the conservatories of the New 
York Botanical Garden, are presented below. 
* The results described in the following paper were obtained by the aid of a Re- 
Search Scholarship in the New York Botanical Garden, in 1903. 
t Nash, G. V. A revision of the family Fouguieriaceae. Bull. Torrey Club, jo: 
449. 1903. 
45 
