STANDLEY TEEES AND SHRUBS OF MEXICO. 933 



28. EPITHELANTKA Weber; Britt, & Rose, Cactaceae 3: 92. 1922. 



A single species is known. 



1. Epithelantha micromeris (Engelm.) Weber; Britt. & Rose. Cactaceae 3: 

 93. 1922. 



MammiUaria micromeris Engelm. Proc. Amer. Acad. 3: 260. 1856. 



Mammillaria micromeris greggii Engelm. Proc. Amer. Acad. 3: 261. 1856. 



MammiUaria greggii Safford, Ann. Rep. Smiths. Inst. 1908: 531. 1909. 



Northern Mexico. Western Texas. 



Plants small, simple or cespitose, nearly globular, but depressed at apex, 

 6 cm. in diameter or less; tubercles very low, small, arranged in many 

 spirals, 1 mm. long; spines nuuierous, white, the lower radials about 2 mm. 

 long, the upper radials on the young tubercles 6 to 8 mm. long and con- 

 nivent over the apex, narrowly clavate, the upper half finally falling off; 

 flowers from near the center of the plant in a tuft of wool and spines; 

 flower very small, whitish to light pink, 6 mm. broad; perianth segments 8 

 to 10; stamens 10 to 15; stigma lobes 3; fruit 8 to 12 mm. long; seeds 1.5 mm. 

 broad. 



The fruits, known as " chilotes," are slightly acid and edible. 



29. H AM ATOC ACTUS Britt. & Rose, Cactaceae 3: 104. 1922. 

 A single species is known. 



1. Hamatocactus setispinus (Engelm.) Britt. & Rose, Cactaceae 3: 104. 1922. 



Echinocactvs setispi)tu'< Engelm. Bost. .Touru. Nat. Hist. 5: 246. ]S45. 



Echinocactus mtiehlenpfordtii Fennel, AUg. Gartenz. 15: 65. 1847. 



Echinocactus liamatus Miihlenpf, Allg. Gartenz. 16: IS. 1884. Not E. 

 hamatus Forbes. 1837. 



Ecliinocactus hamulosus Kegel, Ind. Sem. Hort. Petrop. 34. 1856. 



Echinopsis nodosa Linke. Wochenschr. Giirtn. Pflanz. 1: 85. 1ST^R. 



Echinocactus nodosus Hemsl. Biol. Centr. Amer. Bot. 1: 535. 1880. 



Northern Mexico. Southern Texas, the type collected along the Colorado 

 River. 



Plants up to 15 cm. high, with long fibrous roots ; ribs usually 13, more 

 or less oblique, thin, high, undulate on the margin ; radial spines 12 to 16, 

 slender, often 4 cm. long, some white, others brownish ; central spines 1 

 to 3, longer than radials; flower 4 to 7 cm. long, yellow, with a red center; 

 inner perianth segments oblong, acute, widely spreading; fruit 8 mm. in di- 

 ameter, nearly naked ; seeds 1.2 to 1.6 mm. in diameter. 



30. STROMBOCACTUS Britt. & Rose, Cactaceae 3: 106. 1922. 

 A single species is known. 



1. Strombocactus disciformis (DC.) Britt. & Rose, Cactaceae 3: 106. 1922, 



MammiUaria disciformis DC. M^-m. Mus. Hist. Nat. 17: 114. 1828. 



Echinocactus iurhiniformis Pfeiff. Allg. Gartenz. 6: 275. 1838. 



MammiUaria turhinata Hook, in Curtis's Bot. Mag. 69: pi. 3984. 1843. 



Echinocactus disciformis Schum. in Engl. & Prantl, Pflanzenfam. 3^^: i89, 

 1894. 



Central Mexico ; type from Mineral del Monte, Hidalgo. 



Plants small, depressed, turbinate or semiglobose, 5 to 6 cm. broad ; tubercles 

 somewhat chartaceous, imbricate, more or less winged, bearing 1 to 4 white 

 acicular spines when young, naked when old ; young areoles with white wool, 

 naked in age ; flowers from center of plant, 2 cm. long or less ; scales and 

 outer perianth segments dark red, with whitish margins ; inner perianth seg- 



