Xerophyte

Habit

It makes a cluster of basal stems.

Central Spines

1 to 5 (0 in M. alamensis), dark reddish brown to purplish, the upper part dark blackish brown. 1 to 4 upper ones (if porrect) straight, 8-9 mm long a little stouter and darker, the lower one (or two) elongated and either straight or hooked with upturned hook at end, 1 to 15.cm long.

Seeds

Globose, slightly constricted above base, about 1 mm long, glossy-black and slightly pitted.

Description

Mammillaria sheldoniiSN|8828]]SN|8816]] (Mammillaria grahamii subs. sheldoniiSN|8833]]SN|8810]])is a small cylindrical cactus simple or with several heads from base of the plant, with white radial spines and dark brown hooked centrals. The flowers are pink with darker midviens and typically with green stigmas. It is undoubtedly a variable species, which has given rise to several names now ascribed to synonymy.

Note

This member of the Cactaceae family was given this name in honour of Charles Sheldon (1867–1928), US-American naturalist, once owner of a successful mining business in Mexico.

Tubercles

Cylindrical to conical, four-sided at base, carinate, dull green, 8-9 mm. long, 5-6 mm. wide, without latex, axils without wool but with an occasional few bristles. Tubercule arrangement

Flowers

Large, wide funnel-form, diurnal, inodorous, light purplish-pink with a pinkish brown midstripe and paler margins, about 2 cm. high, 2-3 cm in diameter (up to 3,5 in M. alamensis). Outer perianth segments linear-lanceolate, olive-green at base, brownish green with pinkish green margins above, acute, ciliate. Inner perianth segments about 10, broad, acute, pink to purplish with white margins, to 7 mm wide. Filaments and style light purple. Stigmas-lobes 6 mostly olive green (Orange in Mammillaria pseudoalamensisSN|8816]]SN|8828]]) at times purple-pink.

Blooming Season

Spring ( March-April), and flowers remain open for about three or four days.

Radial Spines

The number of radial spines mostly 12-15, bat varies from as low as 9 (Mammillaria alamensisSN|8810]]SN|8833]]) to as many as 24, needle-like, about 6 to 8 mm long, white, tipped reddish brown with purplish tips,.

Fruits

Club shaped, pale scarlet 25-30 mm long. Edible.