PTI^ROCACTUS. 



31 



k 



Key to Species. 



Seeds narrowly winged; spines up to 2 cm. long . p u:,u...:: 



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



Joints strongly tuberculate , p ^,^l,,; 



Joints scarcely tuberculate. Ji-vfffrt 



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



Ovary loosely covered with stiff spines; wing of seed 2 mm. wide ......'.' 4. P. tuherosus 







.1/^- * ;>i 





f r 



/.'■ . 



'■ % " 



*-j^ 



■^■■-- 



■ '►'-*v^. ' ■'- '^ 



- ^ j» r ."^ t'J'y. rf » > 



I . 



Figs. 31, 32. 

 hickenii. 



Ptcrocactiis 

 X0.7. 



Fig. :^3' 



Pterocactus fischeri. X1.12. Photograph 

 by Paul G. Russell. 



hickenii 



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 flow^er not known; seeds thick, 5 mm. in 

 diameter, with narrow lateral wing. 



Collected by Cristobal M. Hicken 



J 



34 



Figs. 34. 35' 3^>- 



35 



Seeds of three species 

 Natural size. 



36 



doro Rivadavia, southeastern Chubut, 

 Argentina. 



Figures 3 1 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 m spiral ridges somewhat resembling 

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



