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Mammillaria karwinskiana ssp. nejapensis (var. longispina)
This species forms globular stems with silvery white spines up to 5 cm in length, and dense wool and bristles at the areoles.  Each single stem begins to divide dichotomously to form two stems, and will slowly form large clusters.  Some consider this synonymous with M. karwinskiana.
 

Description: Mammillaria nejapensis is very variable, especially for the length of the spines, and  at the beginning there were two recognized varieties: var. brevispina and var. longispina, with respectively short and long spines, but they are merely local or individual variations. This species branches basally or more frequently forms large colonies by dichotomous division.
Stem: Globose to short cylindrical, somewhat wider in the upper part, blue-green to dark green, to 15 cm high and 5 - 7.5 in diameter, with latex.  A cream coloured 'snowy' tomentum is present on the top of the plant.
Tubercle: Tubercles firm, pyramidal with the lacteal juice, arranged spirally with 13-21 parastichys
Axil: With much wool and many tortuous bristles.
Radial spine: Only 3 - 5, awl-like, straight to slightly curved, ivory with reddish-brown tips, becoming chalky white with age, the upper shorter, 2 - 5 mm long, the lowermost the longest, to 25 or even 50 mm (or more) long.
Central spine: Absent.
Flower: Diurnal, funnel-form, 18 mm long, 10 mm in diameter, pale cream with red-brown to scarlet midstripe on each petal. Blooms adorn the crown of the plant, usually in a ring, in the growth of the previous year.
Blooming seson: Spring to summer.
Fruit: Bright or clear red elongated and quite attractive.
Seed: Brown.

M. karwinskiana  is a very variable species, and some of the different growing forms has been for a long time considered a separate and distinguished variety, for example:

• ssp. karwinskiana has medium yellow flowers with purpleish mid-veins, no central spine, and 6 radial spines.
• ssp. collinsii has white flowers with deeper pinkish mid-veins, one central spine, and 7 radial spines.
• ssp. beiselii has white flowers with red tinted mid-veins, one central spine, and 5-8 radial spines.
• ssp. nejapensis also has white flowers with red tinted midv-eins, but the spines are larger and white and have much more wool.  No central spines, and 3-5 radial spines per areole.

Cultivation: It is easy to cultivate and make interesting specimens for any collection, and over time (in 12-15 years) it will form enormous colonies up to 50 cm or more in diameter!  It grows by dichotomously dividing, and also by producing offsets, and doesn't require any special treatment, except for the need for frequent transplanting, in order to manage its exuberance.  It needs as much light as possible without burning the plant, to keep the stems compact.  Provide a well-drained soil mix.  Water well and then allow to dry thoroughly before watering again during the growing season. It doesn't like much, if any, winter water, but can survive short exposures to freezing temperatures (-4° C.) if properly hardened off and kept dry.

Propagation: Mammillaria nejapensis is best propagated from seed.  Seed readily germinates at 20°-22°C, or by offsets if available.

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Scientific name: Mammillaria karwinskiana subsp. nejapensis (R. T. Craig) D. R. Hunt 1997

First description: Mammillaria nejapensis R. T. Craig & Dawson
in: Allan Hancock Found. Occ. Pap. 2: 57 (1948)

Origin:  From Oaxaca city, towards Totalapan, in the NW area around Nejapa. (Rio Totolapan, San Pedro Totalapan-Mitla, Teotitlan, Las Animas, E of Miahuatlan, Los Cantiles, El Camaron-Mitla, San Cristobal, San Luis Amatalan- San Jose Lachiguri, Oaxaca-Tehuantepec)
Altitude 850 - 1.650 m.

Conservation status: Listed in CITES appendix 2.

Synonyms:   

• Mammillaria karwinskiana
  First description by Martius, Nov. Act. Nat. Cur. 16(1): 335 (1832)a
• Mammillaria nejapensis var. brevispina
• Mammillaria nejapensis var. longispina

 Common Names include:  "Owl Eyes" and "Royal Cross"
 

This is one of the Mammillaria commonly called "Owl Eye Cactus", known for dichotomous branching (forking or dividing into two parts). Although dichotomous branching is not a common occurrence in cacti in general, it happens for some reason in this particular subspecies.  What is interesting about this cactus is that it began as a single head, and it has now divided twice, forming what will be four separate branches. When the division process started, it was obvious that four heads would appear, but I don’t think the one head divided quadruply. Most probably, one head became two, and then those two immediately divided.
Other Owl Eye Cactus among others comprise: M. karwnskiana, M. tlalocii and M. perbella.

All the information and photos in cactus art files are now available also in the new the Enciclopedia of Cacti. We hope you find this new site informative and useful.