A shrub about 3 ft high, taller on a wall; young shoots purplish. Leaves 6 to 12 in. long, composed usually of five or seven leaflets. Leaflets lanceolate or narrowly oblong, often unequal-sided, 1 to 31⁄2 in. long, 1⁄4 to 3⁄4 in. wide, each margin set with one to ten slender teeth or sometimes entire, shining green on both sides, stalk of leaflets slender, up to 1 in. long, but sometimes absent (leaflet sessile). Flowers and fruits not freely borne.
This mahonia has been grown in gardens under the erroneous name Mahonia or Berberis “toluacensis”, but it is evidently not the plant described as B. toluacensis in 1869 (see below). The leaflets are usually curiously twisted or even curled, and their stalks vary much in length; one leaflet in a pair may be sessile, the other long stalked; or one leaflet of the pair may be missing. Schneider mentions Zabel’s suggestion that this mahonia might be a hybrid between M. aquifolium and M. fortunei, but this does not seem very likely. It is more likely to have been a hybrid seedling of the plant originally called B. toluacensis (see below). In the texture and colouring of its leaves it recalls M. ‘Undulata’ (q.v. under M. pinnata).
M. toluacensis J. J. (as Berberis toluacensis). – The place of publication of this name is usually given as Gard. Chron. (1868), p. 435, where a writer signing himself ‘J. J.’ asked for information about a plant he had received from a nursery under this name, and believed to be of Mexican origin. It seems to have been overlooked that in the following year the same ‘J. J.’ published the following description: ‘Leaves 6-8 in. long, of 4-6 pairs of leaflets, with an odd one. Leaflets about 2 in. in length by 3⁄4 in. broad, they are ovate-lanceolate, sharp-pointed, sinuated, with 5-6 spiny teeth on each side. The foliage is much like that of B. fascicularis, but not quite so wavy and glaucous. The habit of the plant is more erect, throwing up straight shoots of some length from the base, but in other respects its appearance is such that it might be taken for one of the many garden forms of hybrids which have been raised from “fascicularis”. From the appearance of the leaves of this plant there seems to be no probability of its proving hardy.’ (Gard. Chron. (1869), p. 739.)
The identity of this mahonia can only be guessed at, but it is at least full enough to prove that it cannot be the same as M. ‘Heterophylla’. It is conceivable that the plant described by ‘J. J.’ was really the Mexican form of M. pinnata (M. moranensis) and that it derived from seeds collected near Toluca, west of Mexico City.