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Pelecyphora aselliformis

Hatchet Cactus

Overview

Pelecyphora aselliformis, commonly known as the Hatchet Cactus or Peotillo, is an extremely slow-growing and rare cactus species belonging to the family Cactaceae 1. It is highly prized among succulent enthusiasts for its unique, comb-like tubercle structure that mimics the appearance of a woodlouse.

Taxonomy and Naming

First described by Ehrenberg in 1843, this species serves as the type species for the genus Pelecyphora. The genus name is derived from the Greek word "pelekys" (hatchet), referring to the flattened, hatchet-like shape of its tubercles. The specific epithet aselliformis translates to "shaped like a woodlouse" (Asellus), referencing the unique arrangement of the spines on the areoles 2.

Origin and Habitat

Endemic to the Mexican state of San Luis Potosí, this cactus thrives at elevations of 1,850 to 2,400 meters above sea level. It populates arid and semi-arid scrublands, growing exclusively on limestone-rich gravel slopes and rocky outcrops under harsh, dry conditions 3.

Appearance

The stem is greyish-green, globose to shortly cylindrical, typically reaching up to 10 cm in height and 5 cm in diameter. The highly distinctive tubercles are flattened laterally. The areoles are linear, bearing numerous tiny, scale-like, pectinately arranged spines that form a continuous crust over the tubercle tip. It produces vibrant magenta or deep violet flowers from the apex during spring and summer.

Cultivation and Care

Pelecyphora aselliformis is considered a challenging species in cultivation due to its sensitive root system. It requires an entirely mineral substrate consisting of pumice, lava rock, and limestone grit. Adequate ventilation is crucial, and watering must be carefully regulated. Overwintering must be completely dry and cool 4.

Common Cultivation Mistakes

The most prevalent error is overwatering, particularly in stagnant air or cold conditions, which leads to immediate root rot. Growing this species in standard organic potting soil is often fatal. Lack of adequate light results in etiolation, causing the stem to lose its characteristic compact form.

Bibliography

References

  1. Anderson, E. F. (2001). The Cactus Family. Timber Press. ↩
  2. Backeberg, C. (1977). Cactus Lexicon. Blandford Press. ↩
  3. IUCN Red List of Threatened Species. Pelecyphora aselliformis. ↩
  4. Pilbeam, J. (1987). Cacti for the Connoisseur. Batsford. ↩
Light

Bright Indirect Light

Requires bright, filtered sunlight or light shade during the hottest hours of summer.

Watering

14-45 Days

Extremely dry-tolerant. Water sparingly in spring/summer and keep bone-dry in winter.

Soil

Highly permeable, calcicole, loam-free, pumice-dominated mineral substrate.

Requires a 100% mineral-based, limestone-rich gritty mix with absolutely no peat.

Safety

Pet Friendly

Non-toxic, but the tightly-packed, rigid pectinated spines should be handled with care.

Difficulty

Expert

Highly prone to rot on its own roots; suited for expert growers or grafted plant care.

Native Habitat

Mexico (San Luis Potosí)

Native exclusively to the high-elevation limestone hillsides of San Luis Potosí in Mexico, where it grows tucked among rocks and low desert shrubs.

Frequently Asked Questions

Can Pelecyphora aselliformis be grown indoors?
Yes, but it requires highly ventilated, south-facing windows with intense light. In ordinary indoor rooms, the lack of air movement and high humidity pose a severe rot risk.
How fast does the Hatchet Cactus grow?
It is one of the slowest-growing cacti in the world. It can take upwards of 10 years from seed to reach flowering maturity (about 2-3 cm in diameter).
How often should it be watered?
In summer, water approximately every 14 days, only after ensuring the soil is bone dry. During winter (November to March), water should be withheld completely.
What is the best soil mix for Pelecyphora aselliformis?
Use a 100% mineral-based substrate free of organic matter. A mixture of pumice, lava rock, coarse river sand, and limestone grit is ideal.
How can I encourage it to bloom?
A cold (5-10°C) and completely dry winter dormancy is essential to trigger blooming. In spring, as temperatures rise, it will produce purple flowers from the apex.
Is it toxic to pets?
No, *Pelecyphora aselliformis* does not contain toxic compounds for cats or dogs. However, its rigid, comb-like spines can cause physical irritation.
How do I prevent root rot?
Never use plastic pots; opt for porous terracotta clay pots instead. Keep the soil mix purely mineral and never let water sit in the drainage saucer.
How do you care for a grafted Pelecyphora?
Grafted plants should be watered according to the growth rate and water needs of the rootstock (usually *Hylocereus* or *Trichocereus*), making them faster growers.
Why is this cactus protected in habitat?
It is threatened in the wild by illegal collection and habitat loss. It is listed on CITES Appendix I, and its international trade is strictly regulated.
Can it stay on a balcony in winter?
It can withstand short drops to 0°C to 5°C provided the soil is completely dry, but it must be strictly protected from freezing frost.