N^OMAMMILLARIA . 



137 



More or less cespitose, the individual plants cylindric, 12 cm. long or more; tubercles almost 

 hidden by the spines; radial spines about 30, white, weak, short; central spines 6 to 12, much stouter 

 and longer, more or less ascending, grayish with brown tips; axils of tubercles woolly; flowers borne 

 in a circle about 2 cm. below top of plant, about i cm. long; inner perianth-segments light purple, 

 somewhat spreading at tip, acute; stamens pale, much shorter than the style, purplish above; 

 stigma-lobes narrow; fruit red, clavate; seeds blackish brown, the surface deeply pitted. 



Type locality: Not cited. 



Distribution: In the highlands of the Rio Grande, Texas; Nuevo Leon and Coahuila 

 to Chihuahua and Zacatecas, Mexico. 



This species is widely grown in collections but the flowers are inconspicuous. 



In the Engelmann Collection, now in the Missouri Botanical Garden, is a specimen 

 labeled " Mammillaria pottsii vera — original coll. Dyck. Jan. 1857." This proves to be 

 identical with the plant well known in our collections as M. leona. With specimens of this 

 plant in hand Salm-Dyck's description, which heretofore we had not understood, is clearly 



Fig. 150. — Neomatnmillaria pottsii. 



Fig. 151. — N. mazatlanensis. 



interpreted, except that he states that the tubercle is slightly sulcate above. From the fact 

 that Engelmann says that his specimen is ' ' M. pottsii vera ' ' we suspect that he may have 

 had a plant like M. tuberculosa mixed with it. This seems to have been Poselger's idea, for 

 he refers the plant to Echinocactus, doubtless on account of this supposed groove. The plant 

 which Poselger describes under Echinocactus pottsianus, collected at Guerrero, south of the 

 Rio Grande, is very different from Salm-Dyck's plant; his fragment, also deposited in 

 the Missouri Botanical Garden, consists of a fruit, a few brownish seeds, and a spine-cluster, 

 one attached to the top of a grooved tubercle, and is to be referred to Escobaria tuberculosa, 

 or a related species. The specimen is too fragmentary to identify definitely. Poselger's 

 misunderstanding of Salm-Dyck's plant left the way open for his species, Mammillaria 

 leona, described shortly afterwards. 



The description of the flower and fruit as given by Coulter is doubtless taken from 

 Poselger but does not apply to the true M. pottsii. Our only Texas record is based on J. 

 H. Ferriss's plant from the Big Bend of the Rio Grande, November 15, 1922. 



Coryphantha pottsii occurs in C. R. Orcutt's Circular to Cactus Fanciers 1922 (unsigned 

 and undated) to which he assigns M. leona. 



