Mammillaria of the Month

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Mammillaria hermosana

For many years this newly described (Journal of the AfM 1/2014) species has been in circulation under the name M. schrottii n.n., and it was often viewed as a form of M. lasiacantha. Plants under that name were characterized by the fruit which is partially embedded in the pant body, by the thick fleshy roots, by the almost pectinate spination and by the prominent flower colour. The discovery by Wolter ten Hoeve of a new population where the plants showed even more striking differences with M. lasiacantha led to renewed impetus to study the taxa under the name M. schrottii n.n. in more detail. This study has led to the description of the new M. hermosana.

It comes from the state of Zacatecas, and is limited in population, two main centres so far having being found with relatively small numbers of plants in each. The authors of the new description, Linzen, ten Hoeve et Martínez-Ávalos, have placed this species in the Series Herrerae, along with M. sanchez-mejoradae and M. roemeri.

 Plant of the Month

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Mammillaria longimamma

Mammillaria longimamm in cultivation

Mammillaria longimamma is probably one of the most popular species in the Dolicothele subgroup. It’s large yellow flowers open wide to a diameter of 2-3 inches on a good sunny day.

It comes from the states of Hidalgo and Queretaro, and is especially widespread around the Barrranca de Meztitlan.

It clusters both in cultivation and in habitat, forming mats of long tubercled heads (hence its name) to as much as 30cms or more. The tubercles have variable number of radial spines, between 6 and 10 have been observed, and the typical form has usually a single central spine, occasionally up to 3. It has a well known variety, var. uberiformis, and this has no central spine. This is not consistent, even within a single small group of plants, let alone a population, though a useful descriptive, it is best only used in that way, and not used as a species or subspecies.

Cultivation is quite easy, and it seems to like a reasonably rich compost, though still one with decent drainage. Then it will slowly offset, and reward you with those large flowers in mid summer.

Mammillaria longimamma CD12/129, west of Bellavista del Rio, Qro.

Plant of the Month

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Mammillaria sphaerica

Mammillaria sphaerica in cultivation

Mammillaria sphaerica is fairly obviously related to Mammillaria longimamma, featured in our last Plant of the Month. It is however very distinct in where it comes from, as it's habitat is in southern Texas and Tamauilpas in northern Mexico.

It tends to grow smaller than its southern cousin, clumping less profusely, and making in time a clump of no more that 8" (20cm) or so. It has shorter tubecles, and unlike most forms of it's cousin, has a thick rootstock, though given enough room, it isn't a difficult plant to cultivate.

It is described as clustering, stems to 5cm in diameter, axils slightly woolly, radial spines 12 - 14, whitish to pale yellow, 6-9mm long, straight to slightly tortuous. There is one yellowish central spine, and its flowers are lemon yellow, 6-7cm wide.

Mammillaria sphaerica in habitat nearSan Antonio, Texas, USA

Mammillaria of the Month

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Mammillaria bertholdii

Mammillaria bertholdii is a newly described species (Journal of the AfM, 2/2014), originally discovered in Oaxaca by Andreas Berthold, and described formally in the referenced issue by Thomas Linzen.

It is believed that it is a new member of the Saboe group within the Longiflora Series. The flower would certainly suggest this very strongly. As such, this is the first species in this Group to be discovered south of the volcanic divide, the remaining members originating from Durango and Chihuahua.

It grows close to the ground, and has tubercles and areole resembling those of a Pelecyphora, or indeed with affinities to the areoles of Mammillaria pectifera. However, the flower tube and flower itself clearly show its affinities are with the Saboe group.

It is not expected (and hoped) to come into cultivation for many years, as its habitat is very restricted, and should be classed as critically endangered.

The photos below are courtesy of T. Linzen and A. Berthold.

M. dioica - new form

Mammillaria dioica is a well known and popular species, and it is known to have a number of forms.

Its distribution is very wide, from southern California, USA, to as far as La Paz in the Mexican state of Baja California Sul.

As has been noted in "Mammillaria" by John Pilbeam, it  changes its habit considerably over this extensive range, from thick bodied plants in the north to more narrow stemmed plants in the south.

Its flowers are generally white to yellowish-white, sometimes with a prominent reddish mid-stripe on the petals. However, this form, from far south in Baja California, offers a more consistent pink colour to the flowers. As yet it is not known to have been propagated commercially.

M. scheinvariana

Picture courtesy of Mammillarias.net, permission from Hugo de Cock

M. scheinvariana R. Ortega-Varela & Glass

Body: Plants solitary or sparingly clustering. Stems subglobose, about 5 cm in diameter, 2 - 3.5 cm high, areoles white woolly.

Axils: With fine white hairs.

Radial spines: 20 - 24, to 20 mm long, white, soft, smooth, hair-like, ascending.

Central spines: 1, straight, about 16 mm long, porrect, pale yellowish tan to pale reddish yellow, darker towards tip.

Flower: Funnelform, nearly 2 cm long, about 1 m wide, with palest pinkish white to white margins and tapering faint pink midstripe, filaments bright lavender, anthers whitish.

Fruit: Dark cherry red.

Seed: Shiny black.

Geographic Distribution: Queretaro and Hidalgo, Mexico, in the area now occupied by the Zimapan Dam. Not known to occur elsewhere, and therefore possibly extinct in the wild.

This species was first described in 1997 and was saved from the rising waters of the Zimapan Dam. Its' position within the Stylothelae has been uncertain, with it having been described both as a good species and as a subspecies of Mammillaria crinita. There is also a hook spined plant that is sometimes also assigned to this species name, which is more robust and less obviously soft radial spines. It is believed that this plant is a natural hybrid with another form of Mammillaria crinitia.

Look out for a full article on this interesting member of the Stylothelae soon in our quarterly publication "The Journal of the Mammillaria Society"