A dimorphic shrub up to 10 ft high, armed with spines of two kinds; the one flat, triangular, rigid, frequently 11⁄2 in. wide at the base; the other bodkin-shaped but flattish towards the base, sharply pointed, comparatively slender and from 1⁄2 to 11⁄2 in. long. As a rule the adult plant has the larger, triangular spines only, but in very rare instances the two kinds are found on one plant (see Gard. Chron., 2nd Sept. 1916, fig. 44). These spines, as in other species, are really branchlets producing leaves and flowers in the usual way; they are arranged in pairs, each pair set at right angles to the next. Leaves very small, scanty, or even absent, each one 1⁄4 in. or so long, ovate, toothed. Flowers produced from below the spines singly, in pairs, or occasionally in clusters of four or six; they have no petals and the calyx is tubular, yellowish white, swollen at the base, divided at the mouth into five reflexed lobes; the whole flower and its stalk combined are little more than 1⁄4 in. long. Bot. Mag., t. 5033.
Native of Uruguay; introduced in 1824. This shrub, so uncommon of aspect, is one of the most grotesquely and formidably armed, as well as one of the most interesting of all hardy plants. In the warmer parts of the country it often flowers very freely and attractively in the autumn. It is quite hardy at Kew but is rather shy-flowering there except after fine, warm seasons. It is a curious fact that the plant with the normal flat triangular spines will sometimes, though very rarely, produce shoots with bodkin-like spines.