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. i: 45, B; Palmer, Cult. Cact. 191; Forster, 

 Handb. Cact. ed. 2. 895. f. 122; PfeiflFer, Abbild. Beschr. Cact. 2: pi. 9; Garten-Zeitung 

 4: 182. f. 42, No. 10, as Pfeiffera cereiformis ; Schumann, Gesamtb. Kakteen 611. f. 97, 

 A, B; Bliihende Kakteen 3: pi. 152. 



Plate XXII, figures i and 7, shows flowering branches from a plant collected by Dr. 

 Shafer in Argentina in 19 17 (No. 71), which flowered in April 1919; figure 3 shows the 

 mature fruit. 



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 i. A. micrantha 



Joints usually 4 to 6 cm. broad; spines 4 mm. long or less 2. A. crenala 



Joints serrate 3. A. monacantha 



1. Acanthorhipsalis micrantha (Vaupel). 



Cereus micranthus Vaupel, Bot. Jahrb. Engler 50: Beibl. iii : 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. 



Fig. 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 Cereus, 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 



