History.—This is a tall shrub, native of the western section of the United States. It grows from Colorado to the Pacific Ocean, and is especially abundant in Oregon and the northern part of California. Berberis aquifolium belongs to the section Mahonia of the genus Berberis, which section is considered by some botanists a distinct genus. The following synopsis of the difference between the two sub-genera is taken from “Berberidaceæ” (a pamphlet by C. G. and J. U. Lloyd, 1878):
“The Berberis proper has simple leaves clustering in the axis of a simple or 3-parted spine. The petals have two glands on the inside of each, at the base. The filaments have no teeth. Berries 2 to 3-seeded.
“Mahonia has oddly, pinnately, compound leaves, with no spine at the base, but with spiny-toothed leaflets. The petals are glandless. The stamens have a tooth on each side of the filament, near the top. Berries 3 to 9-seeded.”
The section “Mahonia” is represented in the western United States by six species, viz.: Berberis pinnata, Lag., a tall shrub with the general appearance of B. aquifolium, distinguished from it by the leaflets, which are glaucous underneath, and the lower pair approximate to the base of the petiole; Berberis repens, Lind., a small creeping plant, with leaves often ternate, and leaflets nearly orbicular, and which has been much confounded, and frequently described as Berberis aquifolium. Berberis nervosa, Pursh, a small erect shrub, with leaves often longer than the stem—it appears to be more generally distributed than the other species. The chief characteristics of this species are, the leaflets are three-veined from an oblique base, the common petiole is jointed “like a bamboo stem,” and the flowers are in slender racemes. The two other species, B. Fendleri and B. Fremonti, are of rare occurrence.
Berberis aquifolium and the other species long in use in domestic practice throughout the West, were brought into general notice a few years since by Parke, Davis & Co., of Detroit, who gave the remedy great conspicuity. Dr. Bundy, of Colusa, Cal., wrote many papers on its therapy; these were published in their journal, “New Preparations.” From an examination of the drug, as thrown upon the market, we find the species are confounded, several of them being generally sold as B. aquifolium. The B. nervosa is more commonly met with in these sophistications, but we have likewise noticed B. repens in considerable amount. The confusion is, perhaps, unimportant from a therapeutical point, as all the Mahonias are bitter, and seem to contain berberine in nearly the same proportion (see Related Species).