Origin and Habitat: Sierra Juárez, Oaxaca, Mexico.
Altitude: 3100 metres over sea level.
Habitat: It grows in open pinion forest often embedded in humid moss patches on large exposed rocks.

• Mammillaria deherdtiana var. dodsonii (Bravo) Glass & R.A.Foster
• Bartschella deherdtiana subs. dodsonii (Bravo) Doweld
• Mammillaria dodsonii Bravo

• Mammillaria deherdtiana Farwig
• Bartschella deherdtiana (Farwig) Doweld

• Mammillaria deherdtiana var. dodsonii (Bravo) Glass & R.A.Foster
• Bartschella deherdtiana subs. dodsonii (Bravo) Doweld
• Mammillaria dodsonii Bravo

Description: Mammillaria deherdtianaSN|5387]]SN|5387]] var. dodsonii is a high-altitude form, similar in shape and size to the species but with fewer and longer radial spines. Usually solitary in the wild it clumps readily in cultivation. The flowers are very showy and could well be valued and cultivated by the sophisticated Mammillaria fanciers.
Stem: Spherical-flattened, densely covered by spines, to 3(-4) cm tall 4-5 cm wide, crown depressed or flat.
Tubercles: Prominent, conical, axil usually naked without latex.
Parastichy number: The var. dodsonii has a lower tubercle spiral count 5-8 (usually 8-13 in the standard species)
Areoles: White felted.
Root: Fibrous, lacking the tuberous tap-root commonly seen in its closer relatives.
Radial spines: 20-21, the lowest longest, up to 20 mm long, aciculate, very thin, curved, glassy white.
Central spines: 1-5, stouter, about 10-20 mm long, thin, acicular, nearly erect, straight, variable, light to dark reddish brown with darker tips.
Flowers: Especially beautiful, long funnel-form, up 4 cm wide. Sepals lanceolate, deep brilliant red-violet. Floral tube very long up to 2 cm long. Filaments pink, anthers golden yellow. Style pink, stigmas white.
Blooming season: Spring.
Fruits: Globose 3 to 4 mm diameter half embedded in stems, pale green.
Seed: 2 mm long, black.

Bibliography: Major references and further lectures
1) Nathaniel Lord Britton, Joseph Nelson Rose “Cactaceae: Descriptions and Illustrations of Plants of the Cactus Family” Courier Dover Publications, 1963
2) James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/Aug./2011
3) David Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006 ISBN 0953813444, 9780953813445.
4) Edward F. Anderson “The Cactus Family” Timber Press, 2001
5) John Pilbeam "Mammillaria The Cactus File Handbook" Cirio Pub. Services, 01/Dec/1999
6) Roger Spencer "Horticultural Flora of South-eastern Australia. Volume 2, Flowering Plants: Dicotyledons. Part 1, the Identification of Garden and Cultivated Plants" UNSW Press, 1995
7) Clive Innes, Charles Glass "Cacti" Portland House, 01/May/1991
8) Walther Haage "Kakteen Von A Bis Z: Ein Ratgeber Fur Den Kakteenfreund Mit Kurzbeschreibung Der Wichtigsten Bis Ende 1979 Benannten Gattungen und Arten Von Kakteensowie Der Dazugehorigen Wissensgebiete" Neumann, 1983

Cultivation and Propagation: Mammillaria deherdtianaSN|5387]]SN|5387]] var. dodsonii is relatively rare in cultivation and has the fame to be difficult to grow on its own roots because it is very sensitive to overwatering (rot prone) and slow-growing. However it is more easy than for species deherdtiana.
Growth rate: Slow growing species that will form irregular clumps with time. Flowering 3–5 years from seed.
Soil: Mammillaria deherdtianaSN|5387]]SN|5387]] is adapted to very shallow organic soil (grows in moss patches) and requires skilful cultivation, grow it in an open sandy-gritty cactus compost with more organic matter than usual (e.g. add sphagnum, leaf-mould or fine crushed pine bark)
Pots: It needs a relatively shallow pot to accommodate its fibrous roots and provide a very good drainage. They may stay in the same pot for many years.
Watering: Water in moderation, it prefer a completely dry place during winter. Mature individuals easily rot and die especially after planting so be extremely cautious with watering. , Keep dry in winter or when night temperatures remain below 10° C. Water it less than average if in bigger pots.
Special need: Provide very good ventilation. Nearly all problems occur as a result of overwatering and poor ventilation, especially when weather conditions are dull and cool or very humid.
Fertilization: Feed them once during the growing season with a fertilizer specifically formulated for cactus and succulents (high potash fertilizer with a dilute low nitrogen), including all micro nutrients and trace elements diluted to ½ the strength recommended on the label. They thrive in poor soils and need a limited supplies of fertilizer to avoid the plants developing excess vegetation, which is easily attacked by fungal diseases.
Exposure: It will do its best with lots of sun and become stressed with inadequate light which could result in poor growth and unnatural shape.
Hardiness: It likes warmth (recommended minimum winter temperature 5° C) however plants kept perfectly dry can can survive low temperatures, approx. -5°, but for safe cultivation it is best to avoid freezing temperatures.
Use: This is a good pot plant suited for a non heated green house. It can be also cultivated outdoors in raised beds, terraces if sheltered from winter rain. This cactus continues to be, a particular prize among collectors
Pests & diseases: These cacti may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, there are several pests to watch for:
- Red spiders: Red spiders may be effectively rubbed up by misting the plants from above.
- Mealy bugs: Mealy bugs occasionally they develop aerial into the new leaves and flowers with disfiguring results, but the worst types develop underground on the roots and are invisible except by their effects.
- Scales, thrips and aphids: (they are rarely a problem.)
- Rot: Rot is only a minor problem if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much.
Propagation: Seeds are quite difficult to germinate and a low rate of success. The seeds can be sown in pots of fine, well-drained sandy soil, any time during the spring when temperatures are warm. Cover the seeds with a fine layer of grit and water from below with a fungicide to prevent damping off. For the 1-2 weeks cover the pots with a sheet of glass/clear perspex to keep the humidity levels high. Remove the glass and replace it with light shade-cloth and mist once or twice a day for the next two weeks after which most seeds should have germinated. From then on mistings can be reduced to every second and then every third day as the little plants grow. Grafting is often used to speed growth rate and to create a back-up for plants in collection.