THE CACTACEAE. 



glochids numerous, yellowish, 3 to 4 mm. long; flowers, in only specimen seen, terminal, almost con- 

 tinuous with the stem; ovary tuberculate and spiny like the stem, deeply umbilicate; seed one, large, 

 flat-winged. 



Collected by Walter Fischer in 1914 in the Province of Rio Negro, Argentina, and 

 given to Dr. Rose during his visit to Argentina in 1915 by Professor Cristobal M. Hicken. 



While this species resembles some of the 

 species ofCylindropuntia of theUnited States, 

 the spines are not sheathed. 



Figure 33 is from a photograph of the 

 specimen above cited ; figure 34 shows a seed 

 of the same specimen. 



3. Pterocactus pumilus sp. nov. 



Plants low, usually prostrate or ascending; 

 joints cylindric, i cm. in diameter, covered with 

 weak appressed spines ; areoles very woolly ; flower 

 terminal ; ovary sunk in the apex of the terminal 

 joint, somewhat umbilicate; ovules several; seed 

 flattened, 7 mm. in diameter, very thin. 



Collected by Cristobal M. Hicken (No. 

 3286), January 8, 1914, at Puerto Piramides, 

 Chubut, Argentina. 



Figure 35 shows a seed of above speci- 

 men. 



4. Pterocactus tuberosus (Pfeifler). 



1837. 



Kak- 



()/>//<( Inhcrosa PfcifFcr, Enum. Cact. 146. 

 J'/i-n'i ni /i/^ L'linlzci Schumann, Monatsschr. 



tcenk. 7: 6. 1^97. 

 Ptcrndiclns kniizci Schumann in Engler and Prant', 



Pflan.'enfam. Nachtr. 259. 1897. 

 Plcroftitlu\ ili-i ipicin Giirkc, Monatsschr. Kaktecnk. 



17: 147. 1907. 



Roots tuber-like, single or in clusters, usually 

 small but sometimes large and thick, up to 12 cm. 

 long by 8 cm. in diameter, deep-seated, giving off 

 several erect stems, these branching at surface of 

 the ground; terminal branches purplish, turgid, 

 3 to 40 cm. long, i cm. in diameter, more or less 

 clavate; areoles numerous, small, bearing numer- 

 ous small white appressed spines; flowers terminal, 

 2 to 3 cm. long; petals long, lanceolate, apiculate, 

 yellow; ovary with numerous areoles bearing long 

 bristles; ovules numerous; fruit dry; seeds large, 

 flat, winged, 10 to 12 mm. in diameter. 



Typcloaility: Near Mendoza, Argentina. 



Distribution: Western provinces Of Argen- p, G . 37 ._pteri)cactus Uiberosus. Natural size. Photograph 



tina, chiefly in the mountains. h > Paul G - Russe1 '- 



We have not seen the type of P. kuntzci, 



which is doubtless at Berlin, but we have examined cotypes in the Kurtz Herbarium at 

 Cordoba, Argentina, and at New York. 



Ofitntia titbcrosa, described from Mendoza as long ago as 1837, has long been a puzzle 

 to botanists, who have tried to associate it with various opuntias. Dr. Rose, who visited 

 Mendoza in 1915, found a tuberous-rooted cactus in the mountains above that city, which 

 we are convinced is the plant described by Pfeiffer. There is no doubt, on the other 



