Mammillaria mammillaris (Linnaeus) Karsten (1882: 888)

Hoxey, Paul & Gdaniec, Andrew, 2021, An evaluation of the Cactaceae of Barbados, Grenada, Saint Vincent, and The Grenadines, Phytotaxa 483 (1), pp. 25-74 : 33-40

3. Mammillaria mammillaris (Linnaeus) Karsten (1882: 888) ≡ Cactus mammillaris Linnaeus (1753: 466) ≡ Neomammillaria mammillaris (Linnaeus) Britton & Rose (1923: 70) .

Ind. Loc.:— Rocky places in tropical America. “in rupibus Americae, Curassaviae, aliarumque.” In Linnaeus (1737: 181 no. 1) Lectotype (designated by Mottram 1980: 51): — Plukenet (1691: tab.29 fig.1; image of the lectotype available at https://bibdigital.rjb.csic.

es/viewer/13654/?offset=#page=4).

Description:— Simple or clustering stems, globular to short cylinders, to 8 cm diameter and 20 cm tall ( Fig. 10 ). Tubercles 7–12 mm long, conic, green. Axils slightly woolly but more densely woolly in flowering zone. Areoles about 2 mm diameter, situated on the end of the tubercle. Radial spines 10–16, spreading, 5–8 mm long, light brown or greyish. Central spines similar to radials, 3–6, to 8 mm long, reddish-brown. Flower small, 10–12 mm long, creamy white, barely emerging beyond spines. Fruit clavate, red, 10–20 mm long. Seeds brown.

Distribution in the study area ( Fig. 2C ):— Mammillaria mammillaris does not occur in the main islands of Grenada and Saint Vincent but plants were particularly plentiful on Union island, growing on rocky crags. The northernmost locality known to us is at the northern point of Bequia. This is almost certainly the northernmost locality of this species, as it has not been found further north in the Lesser Antilles. The species is easily overlooked and it probably has a wider distribution than our observations indicate on The Grenadines.

General distribution:— Outside of the Lesser Antilles, this species is found in the Dutch Antilles and also on mainland South America, in Colombia and Venezuela (and offshore islands). The nearest population is reported from Patos Island, now a possession of Venezuela but formally part of Trinidad and Tobago [Patos Island, 1931, Rasool s.n. TRIN 12566!], about 180km from Ronde Island, the southernmost population that we know in the Lesser Antilles.

Discussion:— Howard (1952) failed to mention that this species is present on The Grenadines and he later only reports Mammillaria mammillaris from the island of Canouan ( Howard 1989: 406). Plumier, in his unpublished manuscript, reported M. mammillaris from the islands of Canouan and Carriacou. We confirmed the occurrence of this species only in Canouan. We also discovered M. mammillaris on further islands of The Grenadines, although with fragmented distribution. The species is locally common, but populations are small (usually less than 50 individuals). It favours inaccessible coastal cliffs or steep rocky areas close to the sea. Just once, on Ronde island, did we find it growing in grasses on a ridge with underlying rocky soils ( Fig. 11 ). The plants we encountered had an occasional flower or red fruit, neither of which protrude beyond the spines ( Figs. 12–13 ).

Note of the typification of Mammillaria mammillaris :— The lectotypification proposed by Wijnands (1983), who used the illustration by Commelijn (1697: 105, t.55) is superseded by the previous one given by Mottram (1980: 51).

Figures

FIGURE 2. Distribution of cacti on Barbados, Grenada, Saint Vincent and the Grenadine islands based on observations by the authors. A. Acanthocereus tetragonus. B. Cereus repandus. C. Mammillaria mammillaris. D. Melocactus broadwayi. E. Melocactus intortus. F. Opuntia dillenii. G. Pilosocereus curtisii H. Selenicereus plumieri I. Opuntia dillenii (Barbados). J. Pilosocereus barbadensis (Barbados).

FIGURE 10. Mammillaria mammillaris (Hoxey 1681.03) growing on black volcanic rocks, Canouan.

FIGURE 11 Mammillaria mammillaris (Hoxey 1704.04) growing in grasses, Ronde Island.

FIGURE 12. Flowering Mammillaria mammillaris (Hoxey 1681.03) on Canouan.

FIGURE 13. Mammillaria mammillaris (Hoxey 1704.04) with fruit on Ronde Island.