TORREYA 



April, 1913. 

 Vol. 13 No. 4 



ECHINOCACTUS WISLIZENI ENGEL. AND ECHINO- 

 CACTUS LECONTEI ENGEL. 



By R. E. Kunze 



In regard to these two species, there is a diversity of opinion 

 as to their position as distinct species. Dr. George Engelmann 

 considered them as distinct from each other. The late Dr. 

 K. Schumann united these species and made one a variety of 

 the other. Dr. Schumann had never observed adult plants of 

 either of them, and could not have known how unlike the spines 

 of each are, when the plants are fully matured. Dr. James W. 

 Toumey,* formerly professor of botany in the University of 

 Arizona, at Tucson, also held that these plants were two distinct 

 species. 



I have collected all of my plants of Echinocactus Wislizeni 

 in the river bottoms of Rio Gila, Rio Salado and the Agua Fria, 

 which last named stream is confluent with the Rio Gila 18 miles 

 from Phoenix. The Rio Salado empties its waters into the Rio 

 Gila 15 miles from Phoenix. Echinocactus Wislizeni is usually 

 found very near to the bottom-lands of these rivers, and on the 

 tableland when this is of a sandy and loamy character, as it is 

 for a few miles beyond. Echinocactus Lecontei is generally met 

 with in the foothills of our mountains and when growing on 

 tablelands it prefers the rockiest situations, among boulders of 

 granite or a calcareous formation. Sometimes it is found in 

 very sandy arroyos, or water courses of the tableland, and in 

 such cases the form is that of an obovate plant, while the cylin- 

 drical form always occupies the sides of our foothills and moun- 

 tains. I have collected plants of Lecontei of two meters in 



* Garden and Forest 8: 154. 1895. 



[No. 3, Vol. 13, of ToKREYA, comprising pp. 45-72, was issued 8 March 1913] 



73 



