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Description: Mammillaria sheldonii is
undoubtedly a variable species, which has given rise to several names now
ascribed to synonymy.
The M. pseudoalamensis (= M. alamensis) is nothing else
than a variant recognisable for the absence of central spines,
and larger
flowers with a characteristic distinctive orange pistil.
Habit: It makes a
cluster of basal stems.
Stem: spherical to slender-cylindrical, dull green, often becoming
reddish, 3-6 cm wide, 8-15 cm tall (or more in cultivation)
Tubercles: Cylindrical four-sided basally, carinate, without
latex, axils without wool but with an occasional few bristles.
Tubercule
arrangement: 8 - 13
Radial spines: The number of radial spines varies from as low as
9 (M. alamensis) to as many as 24, white, tipped brown, needle-like,
about 6 to 8 mm long.
Central spines: 1 to 4 ( 0 in M. alamensis), the lower
one
elongated and either straight or hooked, 1 to 15.cm long, brownish, the
upper part dark blackish brown.
Flowers: Large, wide funnel-form, diurnal,
inodorous, light purplish-pink with a pinkish brown midstripe and
paler margins, about 20 cm in diameter (up to 3,5 in M. alamensis).
Stigmas are green (Orange in M. pseudoalamensis)
Blooming season (Europe): Spring, and flowers remain open for about three or four
days.
Fruit: Club shaped, pale scarlet 25-30 mm long.
Seed: black.
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Cultivation: This plant blooms easily and needs lots of light. Use
a pot with good drainage and a very porous
mineral-based potting mix. Potted plants are quite
wet-sensitive, especially in light of its small root
system. Water sparingly during the
growing season, let soil dry in between to prevent root rot,
keep very dry in
winter. Feed
with a high potassium fertilizer in summer.
Usually it is recommended to
over-winter this plant in a bright and warm greenhouse with at least
8-10° C , but it has proven to be quite
frost resistant
(if kept dry it is hardy as low as -7° C). A resting period in winter and strong light are necessary so that it can
flower properly. Plants will offset readily, and
dense clumps can be produced in a very few years.
Propagation: Through seeds and
cuttings. |
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Photo of conspecific
taxa, varieties, forms and cultivars of plants
belonging to the Mammillaria
sheldonii
complex (This
Taxon has lots of synonyms ( like many other cacti),
with several controversial varieties and
subspecies, and comprises a multitude of
different forms, but where each form is linked to others by populations
of plants with intermediate characteristics):
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Cultivation
and Mail Sale 
