A deciduous shrub up to 15 ft high in a wild state, its greyish, glabrous, angled branches armed with slender, simple or three-pronged spines 1⁄4 to 1⁄2 in. long. Leaves produced in clusters of two to seven, obovate to oblanceolate, tapered to the very short stalk, bluntish or rounded at the apex, 1⁄2 to 11⁄2 in. long, half or less than half as much wide, quite smooth and toothless. Flowers 3⁄4 to 7⁄8 in. wide, yellow and pale orange, produced in May either in fascicles, each on its own stalk, or in slenderly stalked umbels, in either case of two to four blossoms. Fruit black, covered with a purple bloom, lemon-shaped, 1⁄4 to 3⁄8 in. long, with the prominent stigma adhering at the end.
Native of the Chilean and Argentine Andes; described by Gay in 1845, but not, I think, established in cultivation until Comber sent home seeds during his Andean expedition of 1925-7. Judging by his wild specimens (No. 798), it must be a very beautiful barberry, especially the form with several flowers borne on a slender drooping main-stalk 1⁄2 to 11⁄4 in. long. The species varies a good deal in this matter of flower-stalks but Mr Comber tells me it is a very unstable character, dependent, he thinks, on such conditions as shade and altitude (Wilson found it to be the same with Japanese cherries).
To the above account, first published in 1933, it should be added that B. montana has proved a quite hardy shrub, with no objection to chalk. It is, however, of rather stiff habit, and inclined to become leggy with age. Whether Comber's No. 798 produced any plants that bear their flowers in umbels (see above) is not known for certain. But as usually seen in gardens B. montana has them in fascicles. They are strikingly large and jonquil-like. It is closely akin to B. chillanensis (q.v.), but that species differs in its downy, more slender stems and, as seen in cultivation, has smaller flowers.
From the Supplement (Vol. V)
The form of B. montana which bears its flowers in umbel-like clusters (Comber 798) has been given the rank of a separate species – B. cabrerae Job.