Scientific Name: Mammillaria
First description by De Candolle, Mem. Mus. Hist. Nat.
Paris 17: 114 (1828)
Origin:Central and northern Mexico (Hidalgo, San Luis Potosi,
Nuevo Leon, Guanajuato, Queretaro)
Habitat: Grows at altitudes of 1200 to
Conservation status: Listed in
CITES appendix 2.
- Cactus sempervivi (DC.) Kuntze
- Mammillaria bachmannii Boed. ex
- Mammillaria caput-medusae Otto ex
- Mammillaria sempervivi v. caput-medusae
(Otto ex Pfeiff.) Backeb. 1961
- Mammillaria tetracentra Otto ex
- Mammillaria tetracantha
Description: Solitary at
first, or slowly clumping flat with ground.
Stem: Flattened globose to depressed globose and not rising much
above ground level, dull grey-green 7.5 cm wide (eventually gets to 10
or 15 cm in diameter)
Tubercles: Pyramidal, firm. The axil is furnished by abundant
wooll. Tubercles arrangement 13 - 21
Radial spines: Mostly hidden under white wool, usually on young
stems only, 2 - 6, white, bristle-like, to 3 mm long.
Central spines: 2 - 3, very short, stout, reddish brown to black,
becoming grey with age, to 4 mm long.
Roots: Taproots large.
Flowers: Funnelform in a rings on the crown barely rising above
the tubercles, whitish to pale yellow with pinkish midstripe, 1-2 cm
long and diameter.
Blooming season: Flowering period spring
Fruits: Club-shaped, red, to 10 mm long.
Remarks: The var. caput-medusae
and var. tetracantha; often mentioned in literature and sometimes
offered in seed lists, should be fully synonymized with the type
Notes: The white wool
between the areoles makes this species a pleasure to look at and grow,
but the diversity among individual specimens is considerable and the
best plants have abundant white axillary wool. Hence, it is worth
raising a batch of seedlings and selecting one or two that have the most
This is a popular slow growing
and easy to cultivate cactus species.
Water regularly in summer, but do not overwater (Rot
prone) Use pot with good drainage and a
very porous potting media, keep dry in winter.
Feed with a high
potassium fertilizer in summer.
It is quite frost resistant if kept dry, hardy as low as -5° C
Outside full sun or afternoon shade, inside needs bright light,
and some direct sun.
Easily flowered. Some plants will slowly offset , and clumps can
be produced in time.
Propagation: Direct sow after last frost.