912 CO^TTRIBUTIONS FEOM THE NATIONAL, HEEBAEIUM. 



3. Myrtillocactus schenckii (Purpus) Britt. & Rose, Contr. U. S. Nat. Herb. 

 12: 427. 1909. 



Cereus schenckii Purpus, Monatsschr. Kakteenk. 19: 38. 1909. 



Puebla and Oaxaca ; type from Sierra de Mixteca, Puebla. 



Treelike, 3 to 5 meters high, with a very stout trunk and many short ascend- 

 ing branches, dark green ; areoles circular, crowded with black felt, about 5 

 mm. apart ; radial spines 6 to 8, straight, 5 to 12 mm. long, black or brownish ; 

 central spine 1, usually 2 cm. long, sometimes 5 cm. long; fruit oblong, 10 to 

 15 mm. long, naked; seeds black, pitted. " Vichisliovo " (Conzatti). 



21. HYLOCEREUS Britt. & Rose, Contr. U. S. Nat. Herb. 12: 428. 1909. 



Climbing cacti, often epiphytic, with elongate stems normally 3-angled or 

 3-winged, and branches emitting aerial roots, the areoles bearing a tuft of 

 felt and several short spines, or spineless in one species ; areoles on seedlings 

 and juvenile growths often bearing bristles; flowers very large, nocturnal, 

 funnelform, the limb as broad as long and as long as the tube or longer; 

 ovary and tube bearing large foliaceous scales but no spines, felt, wool, or 

 hairs; outer perianth segments similar to the scales on the tube but longer; 

 petaloid perianth segments nari-ow, acute or acuminate, mostly white, rarely 

 red; stamens very many, in two series, equaling or shorter than the style; 

 style cylindric, rather stout and thick, the linear stigma lobes numerous, 

 simple or branched ; fruit spineless but with several or many persistent 

 foliaceous scales, mostly large and edible; seeds small, black. 



Numerous other species are found in tropical America. 

 Stems bluish or more or less whitened or gray. 



Spines short, conic 1. H. purpusii. 



Spines acicular 2. H. ocamponis. 



Stems bright green 3. H. undatus. 



1. Hylocereus purpusii (Weing.) Britt. & Rose, Cactaceae 2: 184. 1920. 

 Cereus purpusii Weing. Monatsschr. Kakteenk. 19: 150. 1909. 

 Lowlands of western Mexico, the type from Tuxpan. 



Stems bluish, climbing, elongate, epiphytic; ribs 8 or 4, with horny margins 

 only slightly undulate ; areoles small ; spines 3 to 6, short ; flowers 25 cm. long 

 and nearly as broad wlien fully expanded ; outer perianth segments narrow, 

 purplish ; middle perianth segments golden ; inner perianth segments broad, 

 white except at the golden tips. 



2. Hylocereus ocamponis (Salm-Dyck) Britt. & Rose, Contr. U. S. Nat. Herb. 



12: 429. 1909. 



Cereus ocamponis Salm-Dyck, Cact. Hort. Dyck. 1849. 220. 1850. 



Perhaps native of Mexico ; original locality either Mexico or Colombia ; 

 specimens closely related but probably distinct have been collected in Sinaloa. 



Stems strongly 3-angled, at first bright green, soon glaucous, dull bluish 

 green in age; ribs rather deeply undulate, their margins with a horny brown 

 border ; areoles 2 to 4 cm. apart, borne near the bottom of each undulation ; 

 spines 5 to 8, acicular, 5 to 12 mm. long; flowers 25 to 30 cm. long and fully 

 as broad ; outer perianth segments narrow, long-acuminate, greenish, spreading 

 or reflexed, the innei* oblong, acuminate, white ; ovary covered with imbricate 

 ovate acute purplish-margined scales. 



3. Hylocereus undatus (Haw.) Britt. & Rose; Britton, FI. Bermuda 256. 1918. 

 Cereus undatus Haw. Phil. Mag. 7: 110. 1830. 



Cereus tricostatus Goss. Bull. Soc. Bot. France 54: 664. 1907. 



