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An evergreen tree ultimately 40 ft or more high, the angular young shoots and winter buds minutely downy. Leaves oblong or narrowly oval, tapered at the base, slenderly pointed and spine-tipped, 2 to 5 in. long, 5⁄8 to 11⁄2 in. wide, dull, opaque green, leathery; stalk 1⁄4 in. or less long. Like the common holly it is very spiny on the margins when young, but as the plant attains maturity the spines become fewer and finer, and ultimately the leaves of the upper branches become entire. Flowers very numerous, in dense round clusters in the leaf-axils. Fruits oval, red, large for a holly, commonly two-seeded.
Native of the Himalaya, Assam, Upper Burma, and Yunnan. Whilst inferior to the common holly as an ornamental evergreen, both in the lack of lustre on the foliage, and as rarely bearing fruit, this species is interesting and worth growing for its distinctness. It is perfectly hardy at Kew, where there is a handsome specimen in the Holly Avenue. The largest recorded in Britain grows at Linton Park, Kent; this measures 48 × 51⁄4 ft (1970). There are slightly smaller trees at Leonardslee and Wakehurst Place in Sussex. At Caerhays, Cornwall, there are two trees raised from seeds collected by Forrest in Yunnan (F.25362 and F.25424).
I. dipyrena varies in its leaves, which may sometimes be sparsely toothed or entire. The var. paucispinosa Loes., and var. connexiva W. W. Sm. are founded on such variations, but neither variety is recognised by Dr Hu in her monograph.
I. × beanii Rehd. I. elliptica (Dallim.) Bean, not H. B. K.; I. dipyrena var. elliptica Dallim. – A hybrid between I. dipyrena and the common holly. It resembles the former in general appearance, the leaves being dull green, although shorter and comparatively broader.
specimens: Kew, Holly Walk, 44 × 33⁄4 + 31⁄4 ft (1981); Linton Park, Kent, 54 × 53⁄4 ft (1984); Leonardslee, Sussex, 49 × 43⁄4 ft (1979); Westonbirt, Glos., 44 × 33⁄4 + 31⁄2 ft (1980) and, pl. 1939, 33 × 31⁄2 ft (1983).
I. dipyrena is also in cultivation from Schilling 2139, collected in Nepal in 1976.