An evergreen shrub, usually prostrate and growing into a thick mat only a few inches above the ground; young shoots wiry, glabrous, reddish. Leaves opposite, oval, rounded at both ends, shortly stalked; usually 1⁄6 to 1⁄4 in. long, half to two-thirds as wide; bright dark green, glabrous on both sides, margins decurved. Flowers white, 1⁄4 to 1⁄3 in. wide, produced singly from the terminal leaf-axils, each on a very short stout stalk bearing a pair of more or less leafy bracteoles close to the calyx-tube. Calyx four-lobed; corolla of four rounded petals; stamens usually eight or twelve; fruit an oblong pink berry 1⁄4 in. long, crowned with the persisting calyx-lobes.
Native of the southern parts of S. America, especially in the Straits of Magellan and the Falkland Islands. It has long been known, having been described and named in 1796; it was collected originally by Commerson. Charles Darwin gathered it on Tierra del Fuego in 1833 during the voyage of the Beagle, and many others have found it since then, but it seems to have been comparatively recently introduced. It is well suited for carpeting moist shelves and stones in the rock garden. It is quite hardy south of London. It flowers during November and December in S. America, equivalent to our May and June. The whole plant is rather suggestive of Gaultheria trichophylla.
M. nummularia is one of the six species on which Berg founded the genus Myrteola in 1856. The only character by which this group differs significantly from Myrtus is that the ovary is imperfectly chambered, the partitions not meeting throughout their length. In face of the close agreement in other characters especially the seed and embryo, this difference is not sufficient to warrant generic status. At the most these species would form a section of Myrtus, as was recognised long ago by the famous American botanist Prof. Asa Gray, who referred them to his section Leandria.