8o THE CACTACEAE. 



2. ARIOCARPUS Scheidweiler, Bull. Acad. Sci. Brux. 5: 491. 1838. 

 Anhalonium Lemaire, Cact. Gen. Nov. Sp. 1. 1839. 



Plants spineless,* usually simple, low, with a flat or round top; tubercles tough, horny, or carti- 

 laginous, triangular, imbricated, spirally arranged, the lower part tapering into a claw, the upper or 

 blade-like part expanded ; areoles terminal or at the bottom of a triangular groove near the middle 

 of tubercle, filled with hair when young; flowers appearing from near the center on young tubercles, 

 diurnal, rotate-campanulate, white to purple; fruit oblong, smooth; seeds black, tuberculately rough- 

 ened, with a large basal hilum; embryo described as obovate, straight. 



Type species: Ariocarpus retusus Scheidweiler. 



This genus long passed under the name of Anhalonium, but it was found that Ario- 

 carpus had priority and hence was taken up. Karwinsky proposed the name Stromato- 

 cactus for one of the species, but no description of it was ever published. The genus is 

 usually considered as most closely related to Mammillaria, under which genus two of the 

 species have been placed. Engelmann, who was greatly puzzled over the group, first 

 considered it the same as Mammillaria, then as a subgenus of Mammillaria, and- later as 

 a distinct genus. 



In its small, oblong, naked fruit and straight embryo, it suggests a Mammillaria, but 

 in its tubercles, areoles, seeds, and absence of spines, it is very unlike any of the species 

 of that genus. 



The generic name is from the genus Aria and Kapiros fruit, referring to the Aria- 

 like fruit. We recognize three species, natives of southern Texas and northern Mexico. 



Key to Species. 



Tubercles not grooved on upper side 1. A. retusus 



Tubercles grooved on upper side. 



Plants small, 3 to 5 cm. broad 2. A. kotschouheyanus 



Plants large, 10 to 15 cm. broad 3. A. fissuratus 



1. Ariocarpus retusus Scheidweiler, Bull. Acad. Sci. Brux. 5:492. 1838. 



Anhalonium prismaticum Lemaire, Cact. Gen. Nov. Sp. 1. 1839. 



Anhalonium retusum Salm-Dyck, Cact. Hort. Dyck. 1844. 15. 1845. 



Anhalonium elongalum Salm-Dyck, Cact. Hort. Dyck. 1849. 77. 1850. 



Anhalonium areolosum Lemaire, Illustr. Hort. 6: Misc. 35. 1859. 



Anhalonium pulvilligerum Lemaire, Illustr. Hort. 16: Misc. 72. 1869. t 



Mammillaria areolosa Hemsley, Biol. Centr. Amer. Bot. 1: 503. 1880. 



Mammillaria elongata Hemsley, Biol. Centr. Amer. Bot. 1: 509. 1880. Not De Candolle, 1828. 



Mammillaria prismatica Hemsley, Biol. Centr. Amer. Bot. 1: 519. 1880. 



Mammillaria furfuraceat S. Watson, Proc. Amer. Acad. 25: 150. 1890. 



Cactus prismaticus Kuntze, Rev. Gen. PI. 1: 261. 1891. 



Anhalonium trigonum Weber, Diet. Hort. Bois 90. 1893. 



Anhalonium furfuraceum Coulter, Contr. U. S. Nat. Herb. 3: 130. 1894. 



Ariocarpus pulvilligerus Schumann, Bot. Jahrb. Engler 24: 550. 1898. 



Ariocarpus furfuraceus Thompson, Rep. Mo. Bot. Gard. 9: 130. 1898. 



Ariocarpus trigonus Schumann, Gesamtb. Kakteen 606. 1898. 



Ariocarpus prismaticus Cobbold, Journ. Hort. Home Farm. III. 46: 332. 1903. 



Plants globular or more or less depressed, usually 10 to 12 cm. broad, grayish green to purplish, 

 very woolly at the center ; tubercles horny, imbricated, 5 cm. long or less, ovate, more or less 3-angled, 

 acute to acuminate, often with a woolly areole on the upper side near the tip and this sometimes 

 spinescent; flowers borne at the axils of young tubercles near the center, white or nearly so, up to 

 6 cm. long; outer perianth-segments pinkish, narrow, acute to acuminate; inner perianth-segments 

 at first white, afterwards pinkish, narrowly oblanceolate, with a mucronate tip; stamens numerous, 

 erect; style white; stigma-lobes 9, linear, white; fruit oblong, white, naked; seeds globular, 1.5 mm. 

 in diameter, black, tuberculate-roughened. 



*Sometimes in Ariocarpus retusus small spines are produced in the areoles near the tip of the tubercles. 



tLemaire gives for this species a reference (Herb. Gener. Amat. Nouvel Ser. Misc. 45 ) which we have not been able 

 to locate. Coulter (Contr. U. S. Nat. Herb. 3: 130. 1894) refers this name to Lemaire "Cact. 1839." the Index 

 Kewensis to "Hort. Monv. 1 : 275," and Labouret to "Hort. Univ. 1 : 275, figure," but we have not been able to confirm 

 them. If this name were published in 1839, it would transfer the publication of Anhalonium elongalum Salm-Dyck 

 back to 1845 (Cact. Hort. Dyck. 1844. 15). 



^Reported in the Index Kewensis (Suppl. 1. 263. 1906) as Mammillaria purpuracea. 



