Ariocarpus retusus (furfuraceus) forma major (cv. TAMA BOTAN).
This is a  choice and very priced form with very wide tubercles selected by Japanese growers.
 

Description: The standard A. retusus is a  solitary, slow growing geophyte cactus with tubercles slightly projecting above ground level. The "major" form is a cultivated selection with very wide leaflike, divergent tubercles.
Tubercles: The wide smooth tubercles, with flat surface are the main distinctive characteristic of this priced form, they are 3,5 to 5 cm wide, and are as wide as long or wider in adult specimens.
Stem: Grey, or blue-green, flattened, globose, rounded on top, 3-12cm high, 20-30 cm in diameter.
Flowers: Diurnal 4-5cm in diameter., 2-4 2cm long; white to pink, occasionally with reddish midribs,
Root: Tap root
Flowering time: October
Fruit: White, green, or rarely pinkish, 10-25mm long, 3-10mm in diameter.
Remarks: Ariocarpus retusus is an extremely variable species,. Tubercle size and shape vary widely, a terminal areole is sometimes present at the tip. The vast amount of phenotypic variation in the species has led to the erection of several variants:

Recognized subspecies, varieties and forms:

• A. retusus ssp. retusus: widespread, flowers are cream or white, occasionally with reddish midveins.
• A. retusus ssp. trigonus: somewhat less widespread with long sharp tubercles  twice as long as wide. The flowers are yellow (usually), white to pinkish white.
• A. retusus v. furfuraceus: applied to plants with equilaterally triangular shaped tubercles
• A. retusus ‘furfuraceus’ var. rostratus refers to plants with a more tapered apex to the tubercle.
• A. retusus v. scapharostroides plants from the Villa Juarez region of SLP, it is characterized by erect angular tubercles, superficially reminiscent of A. scapharostrus.
• A. retusus confusus nomina nuda
• A. retusus subsp. jarmilae nomina nuda
• A. retusus subsp. horaceki nomina nuda
• A. retusus var. pectinatus nomina nuda
• A. retusus subsp. panarottoi nomina nuda
• A retusus var. minimus is a nomina nuda which has recently been applied to plants from Echido Nuncio,in San Luis Potosi.
• A. retusus f. major applied to selected cultivated plants with very broad shaped tubercles (“Tama-botan” in Japan).

Scientific name: Ariocarpus retusus Scheidweiler, (1838)
Pubblished in: Bull. Acad. Sci. Brux. 5: 492
"major"  (cv. TAMA BOTAN)

Conservation status: Listed in CITES Appendix I

Synonyms:

• Anhalonium prismaticum Lemaire 1839
• Mammillaria prismatica
• Ariocarpus elongatus Lee 1937Scientific
• Anhalonium elongatum Salm-Dyck 1850
• Ariocarpus pulvilligeris
• Anhalonium areolosum,

Common Names include:  Living Rock, Seven Stars

Origin: Garden origin (Nursery produced cultivar) Japan.
 

Cultivation: This species is slow growing but certainly not as slow as some other types of cacti, it is of easy culture 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. Need 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 6-10 years to reach flowering size, occasionally grafted.

Photo of conspecific taxa, varieties, forms and cultivars of Ariocarpus retusus.

• Ariocarpus retusus
• Ariocarpus retusus forma cristata
• Ariocarpus retusus var. furfuraceus forma mostruosa
•  Ariocarpus retusus (furfuraceus) f. major (cv. TAMA BOTAN)
• Ariocarpus retusus ssp. pectinatus
• Ariocarpus retusus ssp. trigonus
• Ariocarpus confusus ( retusus/trigonus complex )