Mammillaria stella-de-tacubaya

M. stella-de-tacubaya Heese, Gartenflora 53: 214 (1904); Hunt, Bradleya 5: 26-27 (1987); Fitz Maurice, Mamm. Soc. J. 37(2): 24-25 (1997); l.c. Mitt. Arbeitskr. Mammillarienfr. 22(3): 132-137,150,151 (1998)

Series Stylothelae (Series Lasiacanthae acc. Glass & Fitz Maurice)

M. stella-de-tacubaya has been in cultivation for some years, usually labelled as M. gasseriana, and the latter's separate identity from this species where David Hunt maintained it belonged, has been fiercely defended. The Fitz Maurices have studied the problem as part of their thorough, ongoing studies of this Series over several years, and have come up with what I believe to be the correct interpretation of these two separate species. Part of the problem arose from the source of M. stella-de-tacubaya given as merely Tacubaya, Mexico, which for some time has been thought to be the one in Coahuila (there is another in Mexico state). As the Fitz Maurices have pointed out, the plant described, particularly as pictured, does not grow in Coahuila. They have found in Durango a plant matching the described plant, in the area bounded by Mapimi, La Zarca, Santiago Papasquiaro and Nazas; the question of the mystery of Tacubaya is explained by their comment that although there is no Tacubaya shown on the map in this area, there may well have been such a village in 1904. After reviewing the literature and field data with Charles Glass, they all agreed that the Durango plant is what was originally described as M. stella-de-tacubaya.

The plant we have grown for some time in cultivation as M. gasseriana is undoubtedly referable here under M. stella-de-tacubaya, as a glance at the photograph of the originally described plant reveals; this is reproduced in Hunt's A New Review of Mammillaria Names  - note particularly the quite separated, clusters of radial spines and the single, strong, hooked central spine on most areoles. A further look is necessary, for those who doubt the Fitz Maurices' findings, at the photograph accompanying the original description of M. gasseriana (reproduced in Craig's Mammillaria Handbook), which shows a plant with clusters of fine radial spines overlapping each other, and, compared with M. stella-de-tacubaya, quite slender and longer central spines; this equates to what has been described in recent years and is in cultivation as M. viescensis; see further remarks under M. gasseriana.

It is among the most difficult plants to grow successfully in the UK, and is rarely seen larger than a golfball. About 50% grit content in the potting mixture is recommended, and no larger a pot than necessary to house the roots seems to prolong its life, but at any time if overwatered it is liable to succumb.

M. stella-de-tacubaya is described as solitary, 4 to 5cm tall, 3 to 4cm wide, with sparsely woolly axils. Radial spines 35 to 40, bristle-like, interlacing, white, 3 to 5mm long. The solitary central spine (not always present) is hooked, black, 5 to 6mm long. Flowers are reddish white, the outer segments with dark salmon-pink (sometimes olive green) midstripe, about 15mm long, stigmas greenish. Fruit is red; seed black.

Reported as indicated above from the Mexican state of Durango, in the NE, from an area between Mapimi, La Zarca, Santa Papasquiaro and Nazas; by other collectors (as M. gasseriana) from Durango, southern Chihuahua and from Zacatecas, at 1,300 to 2,300m altitude, specifically from Durango, Nazas, W of Mapimi, between Jimenez and Torreon at Conejos, Belem/La Concha, Cerro Blanco/Pe–on Blanco, between Rodeo and Nazas, El Palmito, SE of Cuencame, San Antonio; from Chihuahua, Colorado, Conejos; from just over the Durango/Zacatecas border at Ojo Agua/La Independencia, and farther south at Valparaiso.

Field collection numbers referred here are WAF 2307, 2318, 2319, 2322, 2325, 2359, 2361; Lau 1074, 1176; ML 603, 607, 630, 635, 637; Rep. 1199, 1784, 2325, 2327b; SB 447, 1161, 1164, 1431, 1902; WM 2530, 2541, 4100, 4960, 5753.

Mammillaria stella-de-tacubaya  - among the most difficult of mammillarias to grow successfully in the UK

Mammillaria sheldonii

M. sheldonii (Britton & Rose) Boedeker, Mam. Vergl. Schl. 30 (1933); Britton & Rose, The Cact. 4: 156 (1923) - as Neomammillaria; Foster, Mamm. Soc. J. 7(1): 3 (1967)

Synonyms: M. alamensis, M. gueldemanniana, M. guirocobensis, M. inae/iniae, M. marnierana, M. swinglei, M. swinglei var. diabloa

Series Ancistracanthae

This is undoubtedly a variable species which has given rise to several names now ascribed to synonymy hereunder. I have modified the description below to take account of this.

It is not easy in cultivation (few of this Series are), but the main difficulties seem to arise from overpotting for what is a fairly restricted, fibrous root system, leading to excess water in the potting mixture for too long. Avoid this by providing a shallow pan just large enough to take the root system after the old soil has been shaken out, and using a gritty mixture (up to 50% grit is recommended). If a plant is growing well do not rush to repot too frequently, about every 3 years after the first few annual repottings is enough, often replacing it in the same sized container.

It makes a cluster of slender-cylindric stems to about 15cm (or more in cultivation) tall, about 3 to 6cm wide, axils without wool but with occasional few bristles. 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 8mm long. Central spines 1 to 4, 1 usually hooked, 1 to 15.cm long, brownish, the upper part dark blackish brown. Flowers pale pink or white with pinkish brown midstripe, about 2cm long and wide, stigmas green. Fruit is red; seed black.

Reported from the Mexican states of Sonora, and Chihuahua, up to 1,200m altitude, specifically from Sonora, Hermosillo, Ensenada Chica, Arrieros between Guaymas and Hermosillo, N of Bahia Kino, Guaymas, SE of Empalme, Moritaguaymas, Rio Guchujaqui, Guirocoba, Navajoa, Cerro Masiaca, Ciudad Obregon, Vicam, San Carlos, Boca Abierta, El Novillo, Rio Yaqui, San Bernardo, Fort Pithaya, Esperanza, Minas Nuevas, Guasimas, LibertadÑKino, S of Benjamin Hill?, NW of Tasajera; from Chihuahua, La Bufa/Rio Batopila, Reventon de Ranchito, Rio Chois.

Field collection numbers referred here are Rose et al. 12366 (US 635170, holotype of M. sheldonii), 12568 (US 635832, holotype, as M. swinglei); H.S. Gentry 625, as M. alamensis); Lindsay (DS, as M. gueldemanniana); Craig 289, 844 (US 1730815, type, as M. inaiae); Schwarz 95, as M. marnierana (presumed not preserved); I.M. Johnston 3086 (CAS 81375, US, as M. swinglei); Lau 600, 602, 606; Rep. 210, 216, 217, 218, 220, 221, 223, 561, 562, 567, 569, 570, 571, 573, 807b, 808, 817, 823, 1588, 2089, 2093, 2105, 2108, 2115, 2177, 2180; SB 545, 546, 707; WM 020, 030, 500, 521, 1612, 3151, 4001, 5580, 5591, 6593, 6630?, 6644, 6651, 6720?, 6741, 6851, 8360.

Mammillaria sheldonii is a variable species, having attracted numerous synonyms, but in all its forms is an attractively flowered plant

Mammillaria perezdelarosae

M. perezdelarosae Bravo & Scheinvar, Cact. Suc. Mex. 30(4): 76 (1985); Nava, Cact. Suc. Mex. 34(3): 56 (1989); Fitz Maurice, Cact. Succ. J. (US) 61(6): 165-167 (1989); Pilbeam, Cactus File 1(2): 10-11 (1991); Hunt, Mamm. Postscripts 6: 5 (1997) - as M. bombycina subsp. perezdelarosae

Synonym: M. bombycina subsp. perezdelarosae

Series Stylothelae (Lüthy: Series Bombycinae)

Hunt recently has referred this species to subspecies status beneath M. bombycina, but the Fitz Maurices who have studied this Series over a long period, are of the opinion that it is a good species, with no intermediates between it and M. bombycina found.

Having been lucky enough to have seen both these species in habitat, I am also convinced that they are quite separate, although clearly related. Their habit in the wild is quite different, M. perezdelarosae is solitary or with little offsetting, and no more than about 7.5cm tall and 4.5cm wide, often much smaller, while M. bombycina makes stems of the size seen in cultivation (about 8cm wide and 12cm or more tall), and forms clumps readily of 20 or more stems. The flowers and fruit differ too, with white, exserted fruits in M. bombycina and either small fruits retained beneath the spines or, rarely, exserted red fruits in M. perezdelarosae; and M. perezdelarosae's seed is twice the size of that of M. bombycina. M. bombycina chooses to grow in leaf-litter under oak trees, while M. perezdelarosae seeks out bare or at most moss-covered rock crevices.

The hour or so I spent with this species in the wild, sitting on the edge of a steep-sided canyon, listening to my more agile and foolhardy companions clambering down the rocky sides, was one of those magic times that I find cactus-hunting in Mexico engenders. It is as near to heaven as I am ever likely to get, and my English homeland seemed far away and very crowded and noisy by contrast.

Seedlings raised when it first appeared about 12 years ago have taken all that time to grow into columnar plants about 15cm tall and 6 or 7cm wide, and seem reluctant to offset, although one or two clusters have appeared on the show bench. It is an exceedingly handsome plant with wonderful spination, the centrals contrasting well with the glassy white radials, and the shell-pink flowers completing a colour composition as good as any species, and better than most.

It is described as solitary or clustering, globose becoming cylindrical, about 7.5cm tall, and about 4.5cm wide, axils with bristles, areoles elongated. Radial spines "about 64", while the accompanying excellent botanical illustration shows about 50 (Reppenhagen quotes 46 to 58), pectinate, 2.5 to 3.5mm long, white. Central spines 1 (or 2 to 3), at the upper part of the areole, one hooked, about 10mm long, the other 2, if present, straight or curving, about 6mm long, reddish black (we saw plants with reddish brown spines, and others dark brown, almost black, all paler at the base; and the Fitz Maurices report a westerly locality with a high proportion of plants with yellow spines, a most attractive variant). Flowers white with pink midstripe, to 2cm long, stigmas yellow. Fruit was not described (although a plant was pictured in the German Mammillaria Society's journal with exserted red fruit, it more commonly remains hidden beneath the spines and contains very few seeds); the seed is black or blackish brown.

Reported from the border area of the Mexican states of Jalisco and Aguascalientes, at 2,000 to 2,400m altitude, specifically from Jalisco, Barranca Jala/Lagos de Moreno; from Aguascalientes, from Sierra Fria, especially on the lip or steep sides of canyons, often growing in thick moss, Milpillas de Ariba, Rancho Santa Ana.

Field collection numbers referred here are H. Bravo & L. Scheinvar no. 3938 (MEXU, type); ML 319; Rep. 2311; WAF 1644, 1869.

Mammillaria perezdelarosae one of the most attractive and popular recent discoveries in the genus.

Mammillaria lenta

M. lenta K. Brandegee, Zoe 5: 194 (1904); Bleck, Cact. Succ. J. (US) 42(6): 249 (1970)

Series Lasiacanthae

This is another of those species which has everything to recommend it. It has dense white spines, a very individual, beautiful flower, a slowness of growth that is almost painful, and the capacity to produce a wonderful, show-winning low cluster of stems given patience and skill. I have seen a well-grown clump of this species, about 25cm in diameter, in full flower on every head, take first prize over larger clumps of the more usual competitors (such as M. bombycina, M. plumosa or M. geminispina ) in the "big Mammillaria" class in shows. Such a plant is a much greater tribute to the skill of the grower than the well-grown also-rans - although it must be said that such plants are seldom seen in tip-top condition. What the grower needs, apart from care not to overwater and providing a well-drained soil-mix, is the sense to start growing it when he or she is young.

It is a species which will benefit from maximum exposure to sunlight in England, to ensure compact growth, good spine coverage and a good crop of flowers, which it is otherwise liable to be a little shy in producing.

Although it was described as clustering dichotomously, I have never seen a plant do this. It does make offsets halfway up the very flattened-globose stem, which could give the impression of this, and indeed large clumps of this plant give a similar impression, for instance see the photograph of a plant in the wild in the US Society's journal (ref. above), but no individual head shows any sign of the elongated growing point which precedes dichotomous division. However, as we go to press I have received one unverified report of a plant dividing this way.

Stems are about 3 to 5cm in diameter, as indicated above, very flat-globose, and flat-topped, axils with persistent short wool and an occasional bristle. Spines are all radial, 30 to 40 in number thin, white, slightly yellowish in the young growth, 3 to 7mm long, completely hiding the plant body. Flowers are sometimes difficult to produce in cultivation, and the plant needs good exposure to sunshine to produce them regularly or in quantity; they are about 2cm long, 2.5cm wide, opening widely, white with a thin pink or purplish midstripe on each petal, as though precisely painted with a very thin brush, stigmas olive-green. Fruit is red; seed black.

Reported from the Mexican state of Coahuila, at 900 to 1,400m altitude, specifically from Viesca, Parras, Cuatrocienegas, Cerro Bola, Pinaje de Leone, El Amparo.

Field collection numbers referred here are C. A. Purpus 11 (UC 125367, type); Lau 797; ML 540, 549, 551, 553; Rep. 514a, 704, 1088, 1092, 1184, 1201, 2331; SB 1060, 1719; WM 2240, 2560, 2570, 5550, 7061, 7100, 7110.

The slow growth rate and unusual flowers make Mammillaria lenta one of the most sought-after of species.