PERESKIOPSIS, A NEW GENUS OF CACTACE^E 

 By N. L. BRITTON and J. N. ROSE 



After a number of years observation in the conservatory and 

 field, we are convinced that the subgenus Pereskiopuntia of Opuntia 

 deserves generic rank. Its relation to Pereskia is only slight, 

 although in habit it suggests that genus rather than Opuntia. From 

 Opuntia it is easily distinguished by its habit, its broad, persistent 

 leaves, and its seeds. 



Genus PERESKIOPSIS Britton & Rose, gen. nov. 



Trees and shrubs similar in habit and foliage ro Pereskia, old 

 stems forming a solid woody cylinder covered with bark and re- 

 sembling ordinary dicotyledonous stems; areoles circular, spine- 

 bearing or sometimes spineless, also bearing hairs and glochids ; 

 flowers similar to those of Opuntia; ovary inferior, sessile, leafy, 

 rarely leafless ; fruit red ; seeds few, covered with matted hairs. 



Common in hedges and thickets of Mexico and Guatemala. 



Eleven species are known, of which 9 are now in cultivation in 

 Washington and New York. Two of these species were described 

 as early as 1828 as Pereskias, and here they remained with two later 

 described species until in 1898 Dr. A. Weber transferred them to- 

 Opuntia. 



Type species : Opuntia brandegeei Schum. 



1. PERESKIOPSIS AQUIOSA (Weber) Britton & Rose 



Opuntia aquiosa Weber, Bull. Mus. Hist. Nat. Paris 4 : 165. 1898. 

 Type locality: Cultivated at Guadalajara, Mexico. 

 Distribution : Jalisco, Mexico. 



2. PERESKIOPSIS BRANDEGEEI (Schum.) Britton & xxose 



Opuntia brandegeei Schum. Gesam. Kacteen 653. 1901. 

 Type locality : Near Cape San Lucas, Lower California. 

 Distribution : Southern Lower California. 



3. PERESKIOPSIS CHAPISTLE (Gosselin) Britton & Rose 



Opuntia chapistle Gosselin, Bull. Mus. Nat. Hist. Paris 10:388. 1904. 

 Type locality: Oaxaca, Mexico. 



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