HYWDCEREUS. 183 



Figure 257 is from a photograph taken by C. H. T. Townsend near Chosica, Peru; 

 figure 258 shows a flower and young fruit on the much enlarged areole, collected by Dr. 

 Rose near Arequipa in 1914; figure 259 shows a cluster of spines obtained by Dr. Rose at 

 Chosica, Peru; figure 260 is from a photograph of a top of the Chosica plant brought by 

 Dr. Rose to the New York Botanical Garden. 



Subtribe 2. HYLOCEREANAE. 



Elongated, vine-like, climbing, trailing or pendent, branched cacti, the stems and branches 

 angled, ribbed, fluted, or rarely flat, the joints emitting aerial roots, the areoles usually spiny; 

 flowers mostly large and white, rarely red or pink; perianth -limb regular, or in Aporocactus more or 

 less oblique; fruit a fleshy berry, often large. 



We group the species known to us in 9 genera. 



KEY TO GENERA. 



A. Joints angled, ribbed, winged, or fluted. 



Ovary and fruit covered with large foliaceous scales, their axils neither spiny, hairy, nor bristly; 



flowers mostly large, nocturnal; stems and branches 3-angled or 3-winged. 



Perianth-tube elongated; flowers very large, their scales naked in the axils i. Hylocereus (p. 183) 



Perianth-tube scarcely any; flowers small, some of their scales with tufts of short 



hairs and occasional bristles in the axils 2. Wilmattea (p. 195) 



Ovary and fruit not bearing laige foliaceous scales, their axils spiny, hairy, or bristly. 

 Flowers elongate-funnelform, very large, mostly nocturnal, the tube and ovary 

 usually bearing scales, hairs, or spines. 



Stems ribbed, fluted, or angled 3. Selenicereiis (p. 196) 



Stems winged. 



Areoles of ovary and flower-tube bearing felt and spines subtended by 



short scales; flowers nocturnal 4. Mediocactus (p. 210) 



Areoles of ovary and flower-tube bearing long hairs; flowers diurnal 5. Dcamia (p. 212) 



Flowers short-funnclform or funnelform-campanulate. 

 Perianth-limb regular, the tube stout; flowers white. 



Tube of the flower bearing short foliaceous scales; areoles of the tubercu- 



late ovary bearing long hairs 6. Weberocereus (p. 214) 



Areoles of flower-tube and of non-tuberculate ovary beaiing short black 



spines 7. Werckleocereus (p. 216) 



Perianth-limb somewhat oblique, the tube slender; flowers pink 8. Aporocactus (p. 217) 



AA. Joints flat 9. Strophocactus (p. 221) 



1. HYLOCEREUS (Berger) Britton and Rose, Contr. U. S. Nat. Herb. 12: 428. 1909. 



Climbing cacti, often epiphytic, with elongated 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 narrow, acute or acuminate, mostly 

 white, rarely red; stamens very many, in two series, equaling or shorter than the style; style cylin- 

 dric, 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; 

 cotyledons large, flattened above, thick, ovate, acute, connate at base. 



We know 18 species, natives of the West Indies, Mexico, Central America, and northern 

 South America. Most of them are closely related, having similar stems, flowers, and fruits. 

 Type species: Cactus triaitgularis Linnaeus. 

 The name is from the Greek, meaning forest-cereus. 



KEY TO SPECIES. 



A. Areoles spiniferous; ribs not deeply crenate. 



B. .Stems bluish or more or less whitened or gray. 

 Margin of joints horny. 

 Spines short, conic. 



Outer perianth-segments acuminate, as long as the inner, white ones. ... i. H. guatemalensis 

 Outer perianth-segments acute, much shorter than inner.golden-tipped ones. 2. H. purpusii 

 Spines acicular, slender. 



Outer peiianth-segments linear-lanceolate, acuminate 3. H. ocamponis 



Outer peiianth-segments oblong-lanceolate, obtuse. . . 4. //. bronxensis 



Margin of joints not horny; spines few, conic. 



Branches slender, 4 cm. thick or less, scarcely crenate. 



Stigma-lobes entire . 5. H. polyrhizus 



Stigma-lobes bifid . 51. H. venesuelensis 



Branches stout, 5 to 10 cm. thick 6. //. fusliiriccnsis 



