Mammillaria theresae


No synonyms are recorded for this species name.


Mammillaria theresae is native to Mexico. In particular, it is endemic of the state of Durango, where it can be found in the Corneto Pass Area, in west Sierra Madre, in an area of occurrance of around 25 square kilometers. To date, the estimated number of individuals of the population is just 200. Its habitat are moss patches on limestone rock outcrops, in slopes facing east, into grasslands close to pine-oak (Quercus palustris) forests at an altitude of 2150 to 2300 metres above the sea level.
This species is mainly threatened by illegal collection and habitat degradation, so that it has been listed in Appendix II of the CITES Convention. CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) is an international agreement between governments that has the aim to ensure that international trade in specimens of wild animals and plants does not threaten the survival of the species.
The Appendix II, in particular, lists “all species which, although not necessarily now threatened with extinction, may become so unless trade in specimens of such species is subject to strict regulation.


Mammillaria theresae is a dwarf cacti, very odd and different from any other Mammillaria. Succulent lovers are crazy for this species, for its gorgeous, funnel-shaped, long-tubed bloom, the decorative potential of its spines and its reduced size. The stems, in fact, don’t exceed 4-5 centimeters in height and 1-3 centimeters in diameter. The green stems can take one an intense reddish tinge when exposed to direct, intense sunlight. Like in all Mammillarias, the stem is furrowed with little tubercles which, in this case, are small and rounded-conical to cylindrical. The decorative potential of the spines lies in their being extremely small: to appreciated their starfish-like arrangement, you’ll have to observe them through a lens. From each areole, in fact, are formed only radial spines, which are very short and furry. Spines are very numerous: 22 to 30 per areole! We remind that areoles are the specifical buds of cacti,from which the spines are formed. Looking at the entire plant from a distance without a lens, the thorns cannot be distinguished and only white bumps can be seen, so that the cactus ends up looking like a strange cauliflower. The overall aspect of the plant, moreover, changes during the year: during dry periods, the stem contracts and reduces its dimension, sometimes so much that it ends up to be hidden in the soil and that the flowers literally sprout from the ground. In May, the plant starts to bloom: gorgeous, funnel-shaped flowers with a remarkably elongated tube, unusually long for a Mammillaria, sprout at the top of the stems, grouper in a crown-like structure like in all Mammillarias. They are often bigger than the stems, reaching a diameter of 3,5 centimeters and a length of 5, and they have this bright pink colour that makes them very decorative. Another astonishing feature of this species are its so-called cryptocarpic fruits. Cryptocarpic fruits are special kinds of fruits that ripen inside the stem of the plant. In the specific case of M. theresae, the seeds can remain enclosed in the stem for years or even for the entire lifespan of the plant. Seeds are released and dispersed at a close distance from the mother plant when its stem disintegrates after its death. Sometimes, they might be released before the plant’s death, but always many years after the fruit’s formation.


M. theresae is not among the easiest cacti to grow, like all the Mammillarias of the “samoa” group. However, if you follow a few tips, it will reward you with its wonderful blossoming. Here below are the tips:

M. theresae needs filtered light if grown outdoors as, in its natural habitat, it grows under other bushes, and plenty of light if grown indoors. Sunburnts may occur if it’s exposed to sunlight for too long. however, intense sunlights enhances healthy flowerings.
Mammillaria theresae can resist to extremely cold temperatures if its substrate stays completely dry (down to -12ºC!). However, to stay safe, we suggest to keep it at temperatures of 8-10ºC, and to keep it away from Winter rains. Some authors suggest that plants grown outdoors resist better to winter wetness, but we actually wouldn’t risk.
Provide this plant with a good ventilation: place it exposed to air drafts. During the rest period it shouldn’t be exposed to atmospheric humidity.
Water sparingly during the growth season and be extremely careful, as this plant is very sensitive to root rot. To reduce the risk of rotting, wait always for the soil to dry up completely before every irrigation. In Winter, keep its substrate completely dry.
Mammillaria theresae requires a very well-draining substrate, but with an organic part more abundant than usual. A standard mix for cacti will do good, with some peat or humus.
During the summer, fertilize once with a product specific for cacti, rich in potassium and phosphorus and poor in nitrogen. Nitrogen makes the stem of these plants too watery and fragile and enhances the risk of rotting.
Use a clay pot to enhance drainage and repot every two-three years, as M. theresae is rather slow-growing and will stay ok in the same pot for many years.


Propagation can be carried out either through sowing and cuttings, like in all Mammillarias. This species, by the way, is often found grafted on more tough cacti. Grafting is another valid method of propagation. Seeds must be placed on the surface of a sandy and humid soil at about 20 °C. If you choose sowing as a method of propagation, remember that seeds usually germinate in 8-13 days at temperatures of 21-27ºC. They should be placed in a light substrate and maintained slightly moist and covered with a glass until they germinate. Don’t expose young plants to too intense sunlight. M. theresae can be propagated very easily through cuttings. When it gets sufficiently clustered (you’ll have to wait a little more than usual for this species to produce suckers, unlike in other Mammillarias) and the offsets reach a size of at least 1/3 of the mother stem, you can start to take off them with a sharp knife. Let the cutting dry up for a week or two, until you see that the wound has formed a callous. it in a pot filled with some cactus potting mix. Cuttings will take 4 to 6 weeks to root. It’s important to create a superficial layer of coarse grit and to lie the cutting on it: it prevents the wound to become too wet and, when roots are formed, it allows them to penetrate the compost under it.


Mammillaria owes its name to its tubercles, that look like nipples. The greek word “Mammilla”, in fact, means “nipple”. Mammillaria theresae is one of a number of similar species, all discovered in the 1960s, the others being Mammillaria saboe, Mammillaria haudeana, and Mammillaria goldii. Mammillaria theresae was first described in 1967.

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