208 THE CACTACEAE. 
Subtribe 8. RHIPSALIDANAE. 
Mostly epiphytic cacti, generally growing on trees but sometimes clambering over rocks or 
pendent from them, much branched; branches alternate or often in whorls, slender, terete, angled or 
flat and thin, spineless, except in Pfeiffera and Acanthorhipsalis; flowers regular, mostly small, rotate, 
and without any tube or with a very short tube; stamens usually few, attached to disk or near base 
of flower-tube; style usually short; fruit a small juicy berry, white, red, or purple; seeds minute. 
We have placed this subtribe at the end of our monograph because it appears to us 
to represent the most extreme differentiation within the family. It is indeed difficult to 
explain to most people that its species are really cacti. 
We recognize eight closely related genera. 
Key To GENERA. 
Flowers with a short definite tube. 
Joints terete. 22... ccc ce cece ce cee ee eee ee ee eee ee tect ee ener eeens 1. Erythrorhipsalits (p. 208) 
Joints flattened, ribbed, or angled. ; ; . 
Joints and flowers terminal. ........ 0... ccc cee ec ce cece tence ee eeees 2. Rhipsalidopsis (p. 209) 
Joints and flowers normally lateral. 
Joints with spiny areoles; ovary and fruit with areoles subtended by scales. 
Joints ribbed; fruit-areoles spiny. ......... 0.0... cece ee ee ee eee 3. Pfeiffera (p. 210) 
Joints flattened or 3-winged; fruit-areoles not spiny. ................ 4. Acanthorhipsalis(p.211) 
Joints not spiny; fruit mostly without areoles. 
Upper joints normally flattened; areoles not pilose ................. 5. Pseudorhipsalis (p. 213) 
Upper joints flattened or 3-angled; areoles long-pilose............... 6. Lepismium (p. 215) 
Flowers without tube. 
Petals erect; ends of same joint unlike; flowers and branches always terminal....... 7. Hatiora (p. 216) 
Petals usually widely spreading; ends of same joint usually similar; flowers and 
branches lateral or terminal.........0.. 0.0... cc cece cee cece eee 8. Rhipsalis (p. 219) 
J. / 5) 1. ERYTHRORHIPSALIS Berger, Monatsschr. Kakteenk. 30: 4. 1920. 
Epiphytic, with slender terete stem and branches, often pendent; branches dichotomous or 
sometimes in whorls of 3 to 6; areoles scattered, small, all bearing several bristles; flowers terminal, 
regular, diurnal, white to rose-colored with a short but definite tube; ovary and fruit bristly, the 
latter red; seeds much larger than in Rhipsalis. 
Type species: Rhipsalis pilocarpa Lofgren. 
The generic name is from épvOpés red, and Rhipsalis, referring to the red fruit and 
to the resemblance of this genus to Rhipsalis. Only one species is known. 
The genus resembles in habit some of the species of Rhipsalis with round stems but 
has a distinct flower-tube, on the top of which the stamens are borne. It also differs from 
Rhipsalis in having a long exserted style, exserted even in the bud; in its slowly opening | 
flower (requiring several days to expand); in its very fragrant flower; in having its ovary 
and fruit bearing areoles, each with a cluster of bristles; and in its larger seeds. 
Lofgren, when he described Rhipsalis pilocarpa, was inclined to think that it might 
belong to Pfeiffera. In his latest treatment of it (Arch. Jard. Bot. Rio de Janeiro I: 68) 
he referred it and Pfeiffera ianthothele to Rhipsalis under the subgenus Pfeiffera. 
At the place cited above, Berger proposed that Rhipsalis pilocarpa should be regarded 
as a new subgenus of Rhipsalis but at the same time he incidentally made it the type of a 
new genus. Mr. Berger, who has written most interestingly of it, says in part: 
_ “In 1903, Léfgren made known Rhipsalis pi . 13: to 
which formerly had a fairly wide distribution in oir cilleetions  feccivel in tenn p23 52 $e 0 
the finest specimens coming from the Botanic Garden in Bremen, from which place it was sent for 
naming. The plant grew well in my hothouse but appeared to prefer it cooler and sunnier. The 
habit picture in the Monatsschrift, above cited, is not exactly right. The plant is striking becaus¢ 
of its beautiful bristles; it is very odd. In general it does not differ from the rest of the species of 
Rhipsalis. Because of its beautiful bristles one is persuaded to put it into Ophiorhipsalis. Meantime 
the habit, the flowers, and the fruit show themselves to be a fundamental obstacle. 
In all the species of Rhipsalis which I have had experience with, the ovary and later the fruit 
are entirely naked; at the most there is at times a little scale. In these plants, however, the ovaries, 
which in form remind one of those of C ereus, bear a mass of small tubercles with little scales, in whose 
