PlantFiles: Ball Cactus, Cream Cactus, Cream Pincushion, Flat Cream Pincushion, Heyder's Nipple Cactus
Mammillaria heyderi

There a total of six subspecies:
The subspecies 'heyderi' has 1 central spine and 15-22 radial spines; Flowers are cream color with brownish-greenish midveins.
Subspecies 'gaumeri' has one central spine and 10-12 radial spines; Flowers are plain creamy-white.
Subspecies 'gumifera' has 1-2 central spines and 10-12 radial spines: Flowers are reddish-white with darker midviens.
Subspecies 'hemisphaerica' has 1 central spine and 9-13 radial spines; Flowers are Cream-colored to dusty pink.
Subspecies 'macdougalii 1-2 central spines which are stouter and 10-12 radials spines; Flowers are cream-colored to pale yellow.
Subspecies 'meiacantha' has one to none central spines and 5-9 radial spines; Flowers are pink or white with pink midviens.

Mammillaria applanata
As the name indicates - applanata means 'flattened' - this is a plant of small height, a fairly rare trait in cacti of this genus for most Mammillarias, especially in European cultures, are club-shaped or tall cylindrical forms. Of the related species (Mammillaria heyderi, Mammillaria hemisphaerica and others) Mammillaria applanata is often the flattest, for with a diameter of more than 10 cm it attains a height of only 2.5 to 5 cm and in addition has a depressed crown covered with white wool. The areoles on the flattened, angular tubercles bear 15 to 20 radial spines, whitish, 5 to 12 mm long, and one stronger erect central spine coloured brown with a black tip. The flowers, appearing in May, are about 2 cm long and up to 3.5 cm broad, cream to pinkish on the inside. The fruit is red, more than 3 cm long and contains brownish-red seeds. Mammillaria applanata and related plants have also been named Mammillaria texensis as they grow predominantly in central and southern Texas.