So 
THE CACTACEAE. 
2 . ARIOCARPUS Scheidweiler, Bull. Acad. Sci. Brux. 5: 491. 1838. 
A nhalonium 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 
Tubercles grooved on upper side. 
Plants small, 3 to 5 cm. broad. . 
Plants large, 10 to 15 cm. broad 
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 elongatum 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 furfuraceaX 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 elongatum Salm-Dyck 
back to 1845 (Cact. Hort. Dyck. 1844. 15). 
^Reported in the Index Kewensis (Suppl. 1. 263. 1906) as Mammillaria purpuracca. 
1. A. retusus 
2. A. kotschoubeyanus 
3. A. fissuratus 
