950 CONTRIBUTIONS FEOM THE NATIONAL HERBARIUM. 



34. ECHINOMASTUS Britt & Rose, Cactaceae 3: 147. 1922. 



Plants small, globular or short-cylindric, ribbed, the ribs low,. more or less 

 spiraled, divided into definite tubercles ; areoles bearing several acicular spines 

 with or without stouter central ones ; flowers central, medium-sized, borne at 

 the spine areoles, usually purple; fruit small, short-oblong, scaly, becoming 

 • dry, dehiscing by a basal opening ; scales few, their axils naked ; seed large, 

 muricate, black, with a depressed ventral hilum. 



One other species occurs in Arizona. 



Areoles elongate; with more or less pectinate spines. 



Central spines unlike, one or two of them different from the others. 



1. E. intertextus. 



Central spines nearly alike 2. E. dasyacanthus, 



Areoles circular. 



Central spines subulate, some of them strongly curved 3. E. unguispinus. 



Central spines acicular. 



Plants globular; ribs 20 to 25; radial spines white 4. E. macdowellii.* 



Plants ovoid; ribs IS to 21; radial spines with black tips. 



5. E. durangensis. 



1. Echinomastus intertextus (Engelm.) Britt. & Rose, Cactaceae 3: 149. 1922, 

 Echinocactus intertextus Engelm. Proc. Amer. Acad. 3: 277. 1856. 

 Cereus peetinatus centralis Coulter, Contr. U. S. Nat. Herb. 3: 386. 1896. 

 Ecliinoccreus centralis Rose, Contr. U. S. Nat. Herb. 12: 293. 1909. 

 Northern Mexico. Texas to Arizona. 



Simple, globular or nearly so, 2.5 to 10 cm. in diameter; ribs 13, somewhat 

 acute, more or less divided into tubercles ; areoles 5 to 6 mm. apart, some- 

 what elliptic; spines rigid, red with darker tips; radial spines 16 to 25, ap- 

 pressed, 8 to 15 mm. long, 3 or 4 of the upper radial spines white or nearly 

 so, more slender than the others, almost bristle-like ; central spines 4, subulate, 

 3 of them turned upward and similar to the radials, 10 to 18 mm. long, the 

 other one very short, porreet ; flowers 2.5 cm. long, nearly as broad as long, 

 purplish ; outer perianth segments about 20, broadly ovate, wliite-margined ; 

 inner perianth segments 20 to 25. oblong, mucronate ; fruit nearly globular, 8 

 to 10 mm. in diameter, witli a few scarious scales ; seeds black, shining, 2 mm. 

 in diameter. 



2. Echinomastus dasyacanthus (Engelm.) Britt. & Rose, Cactaceae 3: 150, 



1922. 



Echinocactus intertextus dasyacanthus Engelm. Proc. Amer. Acad. 3: 277. 

 1856. 



Southwestern Texas, the type from El Paso ; doubtless occurring also in 

 Chihuahua. 



Plants cylindric, 10 to 15 cm. high ; ribs somewhat spiraled, made up of nu- 

 merous compressed tubercles ; spines slender, more or less purplish ; radials 

 19 to 25, 12 to 22 mm. long ; centrals about 4, nearly equal ; top of flowering 

 plant and young areoles very woolly ; scales and outer perianth segments red 

 with white margins; inner perianth segments white or purplish, about 2.5 cm. 

 long, acute or acuminate ; ovary bearing a few ovate scales, these naked in 

 their axils. 



3. Echinomastus unguispinus (Engelm.) Britt. & Rose, Cactaceae 3: 150. 1922. 

 Echinocactus unguispimis Engelm. in Wisliz. Mem. North. Mex. 111. 1848. 

 Echinocactus troUietii Rebut, Bait. Cact. Journ. 2: 147. 1895. 

 Chihuahua and Zacatecas; type from Pelayo, Chihuahua. 



