Mammillaria crinita ssp. duwei

Description

Origin and Habitat: This species is found at one location northeast of the city of Guanajuato, Mexico (extent of occurrence and area of occupancy 35 km2).
Altitude range: 1.800 – 2.000 metres above sea level.
Habitat: This species is found on volcanic rock in xerophyllous scrub. Mammillaria duwei is known from only one location, has a small population size, and there is a continuing decline due to overcollection and development. The southernmost of the two known subpopulations of this species has declined as a result of collecting over the past 15 years. Currently the total population is estimated at approximately 500 individuals.

Description: Mammillaria duwei is a small solitary rarely offsetting plants that eventually forms tiny mounds.
Taxonomic Notes: Mammillaria duwei is considered a synonym of Mammillaria crinita by Anderson (2001) and by Fitz Maurice (2002). Considered a provisional species by Hunt (1999) and a subspecies of Mammillaria nana by Pilbeam (1999).
Stems: Heads 3,5 to 6 cm in diameter, 2-4 cm high, dark green, soft, globoid, flattened-globose, to shortly cylindrical.
Tubercles: Small, clavate 4-5 mm high, With a woolly axil and little hair.
Central spines: 0-1 or 2 (occasiaonally 4). The long central spine is not present on all the clones, yellowish, hooked, to 8 mm long, pubescent.
Radial spines: 28-36, acicular, thin, white, brownish at base, pubescent, 3,5-4 mm long, interlacing and densely wrapped against the body of the cactus.
Flowers: Funnel-form, less deeply set, yellowish/cream to light yellow, about 20 mm long and in diameter. Inner segments lanceolate, widely spreading, accuminate, style and stigma lobes greenish.
Blooming season: Flowers readily, and for a long period from spring to the early summer.
Fruits: Light red to red, elongated.
Seeds: Blackish brown.