ZYGOCACTUS. 1 77 



Subtribe 7. EPIPHYLLANAE. 



Mostly epiphj^tic and night-blooming cacti, generally growing on trees, but sometimes on the 

 earth when this is rich in humus, rarely in the crevices of rocks, much branched, spineless (except 

 Eccremocactus and some species of Epiphyllanthus) ; joints seyeral or many, usually flat except at 

 base, often thin, with the areoles borne along the margin (except in Epiphyllanthus) ; flowers 

 regular (except in Zygocactus and Epiphyllanthus); perianth various; filaments usually long and 

 slender; style long and slender; fruit spineless, usually red or purple, either naked or bearing a few 

 scales (rarely many), these usually with naked axils; seeds small, black. 



We recognize 9 genera, diverse both in the plant-body and in the flowers. While 

 apparently not closely related among themselves, the genera forming this subtribe are not 

 any more closely related to other genera, either in the Cereanae or in the Rhipsalidanae. 



Key to Genera. 



Plants branching dichotomously. 

 Perianth irregular. 



Joints thin and leaf-like with toothed margin; areoles all marginal i. Zygocactus (p. 177) 



Joints thick, without teeth, bearing areoles all around 2. Epiphyllanthus (p. 180) 



Perianth regular or nearly so; joints thin ' 3. Schtumbergera (p. 182) 



Plants branching irregularly. 



Perianth-segments spreading or reflexed: flowers mostly large. 



Tube of flower definitely longer than limb 4. Epiphyllum (p. 185) 



Tube of flower not longer than limb. 



Perianth campanulate, its segments few. 



Stamens few ; flowers small 5. Disocactus (p. 201) 



Stamens many; flowers large 6. Chiapasia (p. 203) 



Perianth short-funnelform, its segments many. 



Outer perianth-segments short, obtuse or rounded, the inner white. . . 7. Eccremocactus (p. 204) 

 Outer perianth-segments acute or acuminate, the inner rose or red. ... 8. Nopalxochia (p. 204) 

 Perianth-segments erect; flowers small g. Wittia. (p. 206) 



1. ZYGOCACTUS Schumann in Martins, Fl. Bras. 4': 223. 1890. 



Stems dichotomously much branched, flattened, divided into short joints; flowers terminal, 

 polychromic, irregular; ovary terete, smooth, gradually broadening from base, bearing minute 

 scales at top; flower-tube abruptly bent just above the ovary, ending in a serrate mouth, bearing 

 petaloid spreading scales scattered along its sides; stamens slender, white, arranged in 2 clusters; 

 outer stamens borne along inside of flower-tube from near base to near middle; inner clusters of 

 stamens about 20, arising from center and forming a short tube about base of style with an inner 

 deflexed toothed membrane, upper part free, and all appressed against upper side of flower-tube 

 and upper perianth-segments; style purple, slender, as long as stamens and usually not surrounded 

 by them ; stigma-lobes linear, purple, erect and adhering (so far as we have seen) ; fruit purple, 

 turgid, not at all angled; skin thin; seeds dark brown to nearly black, shining. 



Type species: Epiphyllum truncatitni Haworth. 



This genus has passed for many years under the name of Epiphyllum but that name 

 was wrongly applied to it. One species is here recognized, although several have been pro- 

 posed by previous authors. 



The generic name is from ^vjoi' yoke and kclktos cactus, referring, doubtless, to the 

 peculiarly jointed stems. 



1. Zygocactus truncatus (Haworth) Schumann in Martins, Fl. Bras. 4^: 224. 1890. 



Epiphyllum Iruncalum Haworth, Suppl. PI. Succ. 85. 1819. 

 Cactus truncatus Link, Enum. PI, 2: 24. 1822. 

 Cereus truncatus Sweet, Hort. Brit. 272. 1826. 

 Epiphyllum altensteinii Pfeiffer, Enum. Cact. 128. 1837. 

 Epiphyllum truncatum altensteinii Lemaire, Cact. Gen. Nov. Sp. 76. 1839. 

 Epiphyllum purpurascens Lemaire, Hort. Univ. 2: 349. 1841. 

 Epiphyllum truncatum violaceum Morren, Belg. Hort. 16:260. 1866. 

 Epiphyllum truncatum spectabile Morren, Belg. Hort. 16: 260. 1866. 

 Zygocactus altensteinii Schumann in Martius, Fl. Bras. 4-: 225. 1890. 

 Epiphyllum delicatum N. E. Brown, Gard. Chron. m. 32: 411. 1902. 

 Epiphyllum delicalulum Schumann, Monatsschr. Kakteenk. 13: 9. 1903. 

 Zygocactus deiicatus Britton and Rose, Contr. U. S. Nat. Herb. 16: 260. 1913. 



Joints dark glossy green, about 3 cm. long, sharply serrate, with two prominent teeth at other- 

 wise truncate apex; terminal areole broad and thin, filled with brown wool and bristles; flowers 6 



