PTEROCACTUS. 



KEY TO SPECIES. 



Seeds narrowly winged; spines up to 2 cm. long 



Seeds broadly winged; spines 3 to 10 mm. long. 



Joints strongly tuberculate 



Joints scarcely tuberculate. 



Ovary densely covered with weak spines; wing of seed i mm. wide. 

 Ovary loosely covered with stiff spines; wing of seed 2 mm. wide. . . 



. . i. P. liiikcnii 

 . . 2. P. fischeri 



3- P. i 



4. P. lubcrosus 



FIGS. 31, 32. Pterocactus 



hickenii. Xo.?. FIG. 33. Pterocactus fischeri. Xi.i2. Photograph 



by Paul G. Russell. 



1. Pterocactus hickenii sp. nov. 



Rootstocks moniliform, consisting of at least 4 joints widely separated; joints above ground 

 2 or 3, 2 to 3 cm. long, almost hidden by the spines; spines from each areole numerous, slender, 

 yellow above, brown at base; glochids numerous; fruit and flower not known; seeds thick, 5 mm. in 

 diameter, with narrow lateral wing. 



Collected by Cristobal M. Hicken 

 (No. 3284) January 10, 1914, near Como- 

 doro Rivadavia, southeastern Chubut, 

 Argentina. 



Figures 31 and 32 represent a plant 

 and a seed from the specimen above cited 



2. Pterocactus fischeri sp. nov. 



Stems low, i dm. high or less, spreading or erect, cylindric, 1.5 cm. in diameter, tuberculate; 

 leaves minute, acute; tubercles about as long as broad, arranged in spiral ridges somewhat resembling 

 those of Opuntia u'hipplei; spines numerous, the radials 12 or more, white, setaceous, 6 mm. long, 

 spreading; centrals usually 4, i to 1.5 cm. long, brownish, the tips and bases often yellowish; 



FIGS. 34. 35. 36. Seeds of three species of Pterocactus. 

 Natural size. 



