Mammillaria erythra f. rubber (Now referred to M. mystax) is an
attractive plant with very dark carmine flowers and characteristic
epidermis, which clearly differentiates it from Mammillaria mystax.
M. erythra has a solitary growth and a different body size.
Stem: Dull green, that reddens in full sun, globose with an almost
a flat-topped appearance, 40-90 mm high and 70-300 mm in diameter.
apex is sunken and wooly.
Tubercles: Pyramidal, firm, 4- angled, keeled, 15 - 18 mm long and
12 - 15 mm wide.
The axil has white wool and 3 - 10 short, glassy white
with reddish brown tip, straight bristles
Radial spines: 0 - 8, needle-like, straight, smooth, whitish to
brown, 2 - 6 mm long.
Central spines: 1 - 4, the uppermost the longest, needle-like,
straight or slightly curving, with thicker base, glassy brown with black
up to 50 mm long.
Flowers: Dark carmine, funnel-form, 18 - 22 mm long and 10 - 12 mm
Fruits: Dark carmine, club-shaped, 10 - 15 mm long and 3 - 5 mm
it ripens 5 months after flowering.
Seeds: Brown, flattened keeled, 1,2 mm long and 0,8 mm wide. Hilum
Blooming season: Mainly in spring (and sometimes other
times of year). It doesn't bloom frequently.