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ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 



Pig. 15. — Cepbalo- 

 cereus senilis. 



bristle-like spines. The large white flowers are night blooming, and 

 the fruit contains a few large seeds imbedded in red pulp. 



Cephalocereus, in which the flower-bearing portion is differentiated 

 from the rest in the form of a woolly head, or cephalium, near the 

 apex of the stem, either symmetrical and terminal 

 or one-sided. The fruit (fig. 16), covered with a 

 bare skin becomes shriveled with age. Examples : 

 C ephaloceTeus senilis^ the cabeza de vie jo, or old 

 man's head, of the limestone cliffs of Hidalgo, 

 Guanajuato, and Puebla; C. cometes^ of San Luis 

 Potosi; and G. palmeri ("organo"), of Victoria, 

 Tamaulipas. 



Lophocereus, in which the stem and branches are 

 ribbed very much as in Myrtillocactus, and the are- 

 oles are remote on the sterile portions but crowded 

 on the flower-bearing branches, and on the latter 

 produce short white wool and long stiff bristles. 

 Example : Lophocereus schottii, the sina or sinita 

 (old-man cactus) of Sonora and Lower California. 

 Myrtillocactus, which may be recognized by its short trunk, bluish- 

 green branches curving upward, with six ribs, which form a starlike 

 cross section and are armed with stout dagger-like spines, usually 

 with a stout laterally compressed central and 5 radials about its base. 

 Example: Myrtillocactus geometrizans (pi. 11, 

 fig. 1) which yields the small fruit called 

 " garambullas." 



Pachycereus includes several giant cardones of 

 the Pacific coast region, among them P. j^ringlei 

 and P. pecten-ahoriginum. The first of these 

 may be recognized by the little spheres of yel- 

 lowish tomentum with which its fruit is cov- 

 ered (fig. 17) ; the second by its spiny fruit, 

 resembling great chestnut burs, which the In- 

 dians use for hairbrushes. The seeds of these 

 species are parched, ground, and used for food. 

 The common organo of central Mexico, is placed 

 in this genus by Britton and Rose, under the 

 name Pachycereus Tnarginatus {Cereus gemmatus 

 Zucc). This species is much used for hedges 

 (pi. 11, fig. 2). Its fruit is not edible and the 

 areoles are so close together as to form almost a continuous line along 

 the ribs. The spines are short and inconspicuous and often become 

 obsolete on old plants. Another species belonging here is the tetetzo 

 of southern Puebla {P. columna-trajani) . 



Fig. 1G. — Ceplialoccreus 

 fruit. 



