862 CONTEIBUTIONS FROM THE NATIONAL, HERBARIUM. 



Branching shrub, 1 to 2 meters high ; branches few, glaucescent, deflexed ; 

 leaves spatulate, thick, green, 2.5 to 5 cm. long ; areoles distant, woolly, 

 hairy when young; spines 1 or 2, rigid, white below, 2.5 cm. long; glochids 

 brown, borne in the upper part of the areoles ; flowers red ; seeds white. 



The vernacular name "pititache" has been reported, perhaps erroneously, 

 for this species. 



8. Pereskiopsis pititache (Karw.) Britt. & Rose, Smiths. Misc. Coll. 50: 



332. 1907. 



Pereskia pititache Karw.; Pfeiff. Enum. Cact 176. 1837. 



PeresJcia calandriniaefolia Link & Otto; Salm-Dyck, Cact. Hort. Dyck. 

 1849. 252. 1850. 



Opuntia pititache Weber, Bull. Mus. Hist. Nat. 4: 166. 1898. 



Reported from southern Mexico. 



Stems rather low and somewhat branching ; bark light brownish and flaking 

 off ; areoles on main trunk each bearing 1 to 4 slender acicular spines and a small 

 cluster of yellowish glochids ; branches, even when several years old, bearing 

 a single long acicular spine from an areole and no glochids ; young branches 

 rather slender and green, their areoles small, black in the center, with long 

 white hairs from their margins and no spines; leaves obovate or oblong- 

 obovate, 4 cm. long or less, pale green, thin, acute or bluntish at apex, narrowed 

 at base. 



The names "patilOn" and "pititache" are reported for this species. 



9. Pereskiopsis aquosa (Weber) Britt. & Rose, Smiths. Misc. Coll. 50: 331. 



1907. 



Opuntia aquosa Weber, Bull. Mus. Hist. Nat. 4: 165. 1898. 



Vicinity of Guadalajara, Jalisco. 



Shrub, with glabrous glaucous green branches, the young shoots with long 

 white hairs at the areoles; leaves bright green, nearly elliptic, acute, about 

 twice as long as wide, narrowed at base, glabrous; spines usually solitary, 

 standing at right angles to the stem, white ; glochids few, yellow ; flowers yel- 

 low ; outer petals blotched with red ; fruit pear-shaped, 4 to 5 cm. long, 2 to 

 2.5 cm. in diameter, yellowish green. " Tuna de agua," " pitaya de agua," 

 " chirrioncillo," " tasajillo," " alfilerillo." 



3. NOPALEA Salm-Dyck, Cact. Hort. Dyck. 1849. 63. 1850. 



Much branched plants with definite cylindric trunks ; roots, so far as known, 

 fibrous ; branches or joints flattened, fleshy, often narrow ; glochids usually 

 less abundant than in Opuntia; spines solitary or in clusters at the areoles, 

 sheathless ; leaves small, subterete, soon deciduous ; areoles bearing white wool, 

 glochids, and often spines ; flowers originating in the areoles usually at or 

 near the edges of the joints ; sepals ovate, erect ; petals red or pinkish, erect, 

 closely appressed against the numerous stamens and the style ; filaments and 

 style slender, much longer than the petals ; ovary more or less tuberculate, 

 naked or spiny, with a very deep umbilicus ; fruit a juicy berry, red, edible, 

 usually spineless ; seeds numerous, flat, covered by a hard bony aril. 



Joints without spines 1. N. coclienillifera. 



Joints more or less spiny. 



Spines acicular 2. N. gaumeri. 



Spines subulate. 

 Areoles usually with 1 or 2 spines, but sometimes without spines; joints 

 glaucous 3. N. auberi. 



