ACANTHORHIPSALIS. 211 
Type locality: Montevideo is cited in the original description, but this must be wrong. 
Distribution: Northwestern Argentina, especially in the states of Salta, Tucuman, 
and Catamarca. 
Illustrations: Goebel, Pflanz. Schild. 1: 45, B; Palmer, Cult. Cact. 191; Forster, 
Handb. Cact. ed. 2. 895. f. 122; Pfeiffer, Abbild. Beschr. Cact. 2: pl. 9; Garten-Zeitung 
4: 182. f. 42, No. 10, as Pfetffera ceretformis; Schumann, Gesamtb. Kakteen 611. f. 97, 
A, B; Blithende Kakteen 3: pl. 152. 
Plate xxu, figures 1 and 7, shows flowering branches from a plant collected by Dr. 
Shafer in Argentina in 1917 (No. 71), which flowered in April 1919; figure 3 shows the 
mature fruit. 
/ /2) 4. ACANTHORHIPSALIS (Schumann) gen. nov. 
Small branching cacti, more or less epiphytic, growing on forest trees or creeping over rocks; 
joints flattened or sometimes 3-winged, short or elongated, their margins crenate or serrate; areoles 
spiny; flowers solitary from lateral areoles; perianth-segments united into a short tube; ovary 
bearing on its surface small scales with tufts of felt in their axils, at least in typical species; seeds 
small, black, narrowed at base. 
The type is Cereus micranthus Vaupel and to this genus we have also referred two 
little-known species of Rhipsalis, both of which have flattened joints and spiny areoles. In 
their habit and armament they resemble Acanthorhipsalis micrantha more than they do the 
true species of Rhipsalis. The plants are native of Peru, Bolivia, and Argentina. 
KEy TO SPECIES. 
Joints crenate. 
Joints about 2 cm. broad; spines 5 to 15 mm. long....... 0.2... ce ee ee ee eee eee 1. A. micrantha 
Joints usually 4 to 6 cm. broad; spines 4 mm. long or less...............-++++++++++ 2. A. crenata 
Joints serrate. 0... ee eee ee ee eee eee ee eee e ee tent teen ee eeeee 3. A. monacantha 
1. Acanthorhipsalis micrantha (Vaupel). : 
Cereus micranthus Vaupel, Bot. Jahrb. Engler 50: Beibl. 111: 19. 1913. 
Stems much branched; joints 2 or 3-winged, about 2 dm. long and 2 cm. broad, yellowish 
green, at least when dry; areoles 6 to 10 mm. apart; spines 3 to 10, 5 to 15 mm. long, brown to 
blackish, straight or a little curved; flower, including the ovary, 22 mm. long. 
Fic. 212.—Acanthorhipsalis crenata. 
Type locality: Sandia, southeastern Peru, altitude 2,100 meters. 
Distribution: Known only from the type locality. 
This plant was described by Dr. Vaupel as a species of C ereus, but as he writes us 
under date of October 20, 1920, it is of course not a Cereus in the stricter sense, but is more 
