An evergreen shrub up to about 15 ft high in this country; branches occasionally spine-tipped, green or purplish when young, glabrous. Leaves short-stalked, elliptic to broadly so, or oblong or lanceolate, more rarely obovate or ovate, cuneate at the base, obtuse to rounded at the apex, 5⁄8 to 2 in. long, mostly 3⁄16 to 9⁄16 in. wide, rarely to 3⁄4 in. wide, entire or more or less toothed, glabrous on both sides; petioles to 3⁄16 in. long. Flowers very small, about 1⁄6 in. wide, greenish white or greenish yellow, borne in May in axillary racemose clusters 1⁄2 to 1 in. long. Fruits in dense clusters, each one a dry, deep purple drupe about the size of a peppercorn.
Native of S. America, where it is widespread from Bolivia, Peru and Brazil south to Chile, Uruguay and Argentina; introduced in 1790. It is a very variable species in foliage, degree of spininess and in the size and shape of the inflorescence; the above description is based on the cultivated states, of which there have been many in British gardens, though the species is now rare. The form depicted in Bot. Reg., t. 1573 (1833), as Duvaua dependens, probably represents the original introduction from Chile, with small obovate leaves obtuse or emarginate at the apex. This was perfectly hardy on a wall and set seed. In Bot. Reg., t. 1568 is figured (as Duvaua ovata) a form with ovate, distinctly toothed leaves – even with a small lobe on each side near the base. This form is also figured in Bot. Mag., t. 7406, as S. dependens. This form, also from Chile, is also hardy or almost so, and is probably what has been commonly cultivated as S. dependens.
Another introduction of S. polygamus was described in previous editions under the name S. bonplandianus. This had linear-oblong leaves 3⁄4 to 2 in. long, 1⁄4 in. wide, entire or sparsely toothed. It was introduced from Argentina by Low of Clapton about 1830 and was slightly tender.
S. latifolius (Gillies ex Lindl.) Engl. Duvaua latifolia Gillies ex Lindl. – Closely allied to S. polygamus. Branchlets not spine-tipped. Branches glabrous or clad with spreading white hairs. Leaves ovate, narrowly ovate or broad-elliptic, rounded or truncate at the base, acute to rounded at the apex, mostly 13⁄4 to 23⁄8 in. long and 3⁄4 to 13⁄8 in. wide, deep green above, light green below, downy or glabrous on both sides, prominently veined beneath, margins undulate and toothed. Introduced before 1829. It was hardy at Kew on the Temperate House Terrace.
The flowers of these two species have no bright colour to recommend them, but they are borne in such profusion that the shrub gives quite a pleasing effect. The leaves and other parts have a turpentine-scented sap, and from this derives what Loudon calls ‘a pretty phenomenon’. It was described by Lindley as follows: the leaves or parts of leaves, when placed in water, ‘after lying a short time, will be found to start and jump as if they were alive, while at the instant of each start a jet of oily matter is discharged into the water … Thus we have in every leaf a sort of vegetable battery, which will keep up its fire until the stock of ammunition is exhausted.’