Origin and Habitat: Mexico (Tamaulipas, Nuevo Leon)
Habitat: Grows in limestone at 600-1200 m of elevation, mostly found in colonies of considerable size, the habitat length is over 400km.

• Ariocarpus retusus subs. trigonus (F.A.C.Weber) E.F.Anderson & W.A.Fitz Maur.
• Anhalonium trigonum F.A.C.Weber in Bois
• Ariocarpus trigonus (F.A.C.Weber) K.Schum.

• Ariocarpus retusus subs. trigonus (F.A.C.Weber) E.F.Anderson & W.A.Fitz Maur.
• Anhalonium trigonum F.A.C.Weber in Bois
• Ariocarpus trigonus (F.A.C.Weber) K.Schum.
• Ariocarpus retusus subs. horacekii Halda & Panar.
• Ariocarpus elongatus subs. horacekii (Halda) Halda
• Ariocarpus trigonus var. horacekii Halda
• Ariocarpus trigonus var. minor M.Voldan

• Ariocarpus retusus Scheidw.
• Anhalonium areolosum Lem.
• Anhalonium prismaticum Lem.
• Anhalonium pulvilligerum Lem.
• Anhalonium retusum Salm-Dyck
• Cactus prismaticus Kuntze
• Mammillaria areolosa Hemsl.
• Mammillaria prismatica Hemsl.
• Ariocarpus confusus Halda & Horáček
• Ariocarpus retusus subs. confusus (Halda & Horáček) Lüthy
• Ariocarpus elongatus (Salm-Dyck) Wettst.
• Anhalonium elongatum Salm-Dyck
• Ariocarpus trigonus var. elongatus (Salm-Dyck) Backeb.
• Mammillaria elongata (Salm-Dyck) Hemsl.
• Ariocarpus furfuraceus C.H.Thomps.
• Anhalonium furfuraceum J.M.Coult.
• Ariocarpus retusus var. furfuraceus (S.Watson) G.Frank
• Mammillaria furfuracea S.Watson
• Ariocarpus furfuraceus f. cristata Frič
• Ariocarpus furfuraceus f. monstruosus hort.
• Ariocarpus furfuraceus var. rostratus A.Berger
• Ariocarpus prismaticus hort. ex Cobbold
• Ariocarpus pulvilligerus K.Schum.
• Ariocarpus retusus f. cristata hort.
• Ariocarpus retusus subs. jarmilae Halda, Horáček & Panar.
• Ariocarpus retusus subs. panarottoi Halda & Horáček
• Ariocarpus retusus subs. pectinatus Weisbarth
• Ariocarpus retusus subs. scapharostroides Halda & Horáček
• Ariocarpus retusus var. sladkovskyi Halda & Kupčák
• Ariocarpus retusus subs. sladkovskyi Halda & Kupčák
• Ariocarpus retusus var. elongatus (Salm-Dyck) Backeb.

• Ariocarpus retusus cv. Cauliflower
• Ariocarpus retusus cv. Cauliflower King
• Ariocarpus retusus cv. Frumdosus
• Ariocarpus retusus cv. Frumdosus brevituberosus
• Ariocarpus retusus cv. Frumdosus f. variegata
• Ariocarpus retusus cv. Maruibo
• Ariocarpus retusus cv. Maruibo Cauliflower
• Ariocarpus retusus cv. Maruibo Pectinatus
• Ariocarpus retusus cv. Mituibo
• Ariocarpus retusus cv. Three Finger
• Ariocarpus retusus cv. Trefinger
• Ariocarpus retusus cv. Royal Tama Botan
• Ariocarpus retusus cv. Tama Botan
• Ariocarpus furfuraceus cv. Tama Botan
• Ariocarpus retusus f. major

Description: Ariocarpus trigonusSN|2078]]SN|2094]] is one of the largest species that distinguishes for the long leaf-like triangular tubercles and peculiar yellow flowers. It is quite variable in tubercle shape and size and has received numerous unnecessary names of no botanical value, representing no more than local phenotypes
Habit: Solitary rosette-forming, geophytic cactus rising slightly above ground level.
Stem: 5 to 30 cm in diameter, 4 to 25 cm tall, globose, more or less depressed, rounded on top, mostly yellowish-green.
Tubercles: Upright yellow/brownish grey, divergent, not closely set or basally compressed, acute at the apices, flattened and smooth adaxially, not fissured, strongly incurved, 3-8cm long, 1-2.5cm broad, usually twice as long as wide, but variable from long and thin to short and broad.
Areoles: Ariocarpus trigonusSN|2079]]SN|2094]] bears only small basal areoles, whose meristem do not divide, monomorphic. On the contrary Ariocarpus retususSN|2094]]SN|2079]] has floral and spinous parts separate, dimorphic. However spine-bearing portions of the areoles are present at the tips of the tubercles of tubercles only in very small specimens.
Roots: Tap root.
Flowers: Cream-white to yellowish-white or yellow (occasionally with reddish mid-ribs) with a satin sheen, 3 to 5 cm in diameter up to 4 cm long.
Blooming season: They come in late autumn or early winter.
Fruit: Whitish or greenish, 7-20 mm long, 5-10 mm across.
Remarks: In the area of Aramberri Ariocarpus trigonusSN|2079]]SN|2094]] intergrades with Ariocarpus retususSN|2094]]SN|2079]] giving rise to a an hybrid population known as Ariocarpus confususSN|2094]]SN|2078]]

Bibliography: Major references and further lectures
1) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
2) Del Weniger “Cacti of the Southwest: Texas, New Mexico, Oklahoma, Arkansas, and Louisiana” University of Texas Press, 1969
3) James Cullen, Sabina G. Knees, H. Suzanne Cubey "The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass" Cambridge University Press, 11/Aug/2011
4) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
5) Urs Eggli, Leonard E. Newton: “Etymological Dictionary of Succulent Plant Names” Springer, Berlin/Heidelberg 2010
6) N. L. Britton, J. N. Rose: “The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family.” Volume III, The Carnegie Institution of Washington, Washington 1922
7) E. F. Anderson and W. A. Fitz Maurice "Ariocarpus revisited." Haseltonia 5: 1-20. 1997).
8) Anderson, E. F. "Ariocarpus: Some reminiscences." Cart. Succ. J. (US) 71:180-190, 1999)
9) Stuart Max Walters “The European garden flora. 3.[Angiospermae], Dicotyledons. [Casuarinaceae to Aristolochiaceae]” Cambridge University Press, 1989

Cultivation and Propagation: This species is slow-growing, but certainly not as slow as some other types of cacti. It is of easy cultivation in a well drained, non-organic, free-draining soil compost, with ample water during the growing season. Use of a weak low-nitrogen fertilizer during the growing season can encourage growth. The main threat to their development is root rot. Ariocarpus should be kept dry whenever there is a threat of cold. The appearance of Ariocarpus can benefit greatly by watering the plants from the bottom. This practice will help to keep the “wool” on the top of the plant from becoming matted or discoloured. Needs light shade to full sun. Frost Tolerance: Hardy to -10° C.
Propagation: It is probably the easiest species of the genus to raise from seed, but will generally take about 7-10 years to reach flowering size, occasionally grafted.