CACTACE^ OF MEXICO SAFFORD. 



547 



needle-like brown spines protrude. This species is locally known as 

 " alfilerillo,'' or "tasajillo," from its resemblance when leafless to 

 the true tasajillo ( Opuntia leptocaulis) . Other species are the slender- 

 stemmed Pereshiopsis spatliidata^ P. pititaclie of Tehuantepec, the 

 very similar P. hrandegeei of Lower California, P. cliapistle of 

 Oaxaca, and P. porteri^ the " yellow rose " of Sinaloa. 



2. Ojmntia. — Formerl}^ this genus was divided into two sections; 

 Platopuntia, including plants with flattened joints; and Cylindro- 

 puntia, with joints cylindrical or terete. Various other classfica- 

 tions have been proposed, the latest and most satisfactory of which 

 is that of Britton and Eose,'' who divide the genus into a number of 

 groups which they call " series." 

 Among those occurring in Mexico 

 are the following: 



Clavatse, in which the joints 

 are cylindrical or clubshaped and 

 the spines unsheathed. Examples : 

 Opuntia hulhispina, a prostrate 

 species with spines bulbous at the 

 base, often forming thickets in the 

 State of Coahuila, north of Par- 

 ras; Op>untia emovyi of Chihuahua 

 and Sonora; and Opuntia hrad- 

 tiana {Cereus hradtianus Coult.), 

 a cereus-like erect species growing 

 in Coahuila. 



Cylindracese, with compara- 

 tively stout joints, and spines 



Fig. 12 



1 ii 1 • 11 1 -IT r Hi. 1.-. — Ta.sa.yi\\o (Opuntia leptocauUs.) 



sheathed m scabbards, including 



the coyonostlis, or cardenches, Opuntia imhricata and O. arhorescens, 



and the clavellinas, or abrojos, Opuntia tunicata (pi. 10, fig. 5). 



Monacanthse, also with sheathed spines but with slender-branched 

 stems and a bushy habit of growth; including the tasajillos of north- 

 ern and central Mexico Opuntia leptocaulis (fig. 12), with scarlet or 

 coral-red fruit, and 0. kleinicp, with somewhat stouter stems and 

 yellowish fruit. An interesting feature of these plants is that the 

 fruit is often proliferous; that is, branches and flowers frequently 

 grow from the areoles of the cuticle covering the fruit itself. 



Pubescent es, with pubescent joints and sometimes without spines, 

 though usuall}^ rich in bristles; including Opuntia 7mfida and 0. 

 microdasys (pi. 10, fig. 4), usually called " nopalillos cegadores," 



°- Britton and Rose. A preliminary treatment of the Opuntioideae of North 

 America. Smithsonian Misc. Coll., vol. 50, p. 503. 1908, 



