Ariocarpus retusus "pectinata"
 
 

Description: This plant differs from the standard Ariocarpus retusus, for its short pectinated spines already present in young specimens. The spines persist with the age, but in adult plant they are partially covered by fur.
Stem: Dull green , flattened, globose, rounded on top, 3-12cm high, 10-15cm in diameter.
Tubercles: Leaflike divergent, erect, basally compressed, becoming attenuate at the apices, convex or nearly flattened adaxially, 1.5-3cm long, 1-3cm broad, usually nearly as broad as long (or sometime longer than broad)
Spines: 1,2 to 2,0 mm long, dull.
Areoles: At the tips  and extending on the upper side of the tubercles, elongated from 2,5 to 20,0 mm long, wooly.
Flowers: Diurnal 4-5cm in diameter., 2-4 2cm long; white to pink
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 subsp. Pectinatus Weisbarth Subspec. nov. (nomina nuda)
Manfred Weisbarth a new subtype of Ariocarpus (Cactaceae), Nov. 2003, 11, 289-292.

Type: Holotype: Mexico, San Louis potosi, To Huizache (?), A. Lau s.n. of 1971 cultivated specimen, Weisbarth (ULM 17099).

Conservation status: Listed in CITES Appendix I

 Synonyms:

• Ariocarpus retusus var pectinatus

This odd plant has long adiaxal areoles that stretch out to a greater or the full length of the tubercle and uncommon short pectinated spines .

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: Ariocarpus retusus is probably the easiest species of the genus to raise from seed, but will generally take about 6-10 years to reach flowering size, this rare form is frequently grafted to speed the growth rate.

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 )