Subspecies, varieties, forms and cultivars of plants belonging to the Mammillaria heyderi group
Mammillaria heyderiMuehlenpf.: It has 1 central spine and 15-22 radial spines; Flowers are cream coloured with brownish-greenish mid-veins.
Mammillaria heyderi var. applanata(Engelm.) Engelm.: It is often the flattest but otherwise very similar to the The ssp. heyderi and may probably repesent only a race of the same species.
Mammillaria heyderi subs. gaumeri(Britton & Rose) D.R.Hunt: It has one central spine and 10-12 radial spines; Flowers are plain creamy-white.
Mammillaria heyderi subs. gummifera(Engelm.) D.R.Hunt: It has 1-2 central spines and 10-12 radial spines: Flowers are reddish-white with darker midviens.
Mammillaria heyderi subs. macdougalii(Rose in L.H.Bailey) D.R.Hunt: It has 1-2 central spines which are stouter and 10-12 radials spines; Flowers are cream-colored to pale yellow.
Mammillaria heyderi subs. meiacantha(Engelm.) D.R.Hunt: It has one to none central spines and 5-9 radial spines; Flowers are pink or white with pink mid-viens.
Mammillaria meiacanthais a low-growing species, up to 6 inches or more in diameter but usually just a couple of inches tall, and often partly obscured by grass or other vegetation. During dry spells the height is reduced further, to or even below the ground level. Spine clusters are borne on elongated, closely spaced green tubercles, and they consist of a single central spine, angled upwards, and between 5 and 9 (usually 6 or 7) radial spines. All spines are similar in length (up to half an inch), and color (light grey, brownish red or pinkish, with darker tips), while the centrals are only slightly thicker than the radials.
Flowers grow between the tubercles in several rings near the top of the plant, opening in stages over several months in spring. Flowers have light green stigmas, pale yellow stamens and white or pale pink petals, darker down the middle. Fruits are colored purple or pink, and appear later than most other cactus species, between October and March.
