Berberis japonica
Introduction '''''Berberis japonica''''' is a species of flowering plant in the family Berberidaceae, native to Taiwan. Despite the name, it is not native to Japan, though it has been known in cultivation there for centuries. The wild origins of this species have long puzzled botanists, but wild plants in Taiwan, previously known under the name ''Mahonia tikushiensis'', appear most similar to the cultivated forms of ''B. japonica''.
Description It is an evergreen shrub growing to  tall by  wide. The foliage is pinnate, glossy dark green above, paler beneath, and sharply toothed. Each leaf usually has six to eight pairs of leaflets together with a single terminal leaflet. The plant produces new shoots regularly from the base, so it is clothed in foliage at all levels.The small, scented, yellow flowers are borne from autumn through winter into spring. The inflorescences are 25 cm or more long, at first arching and then pendant. Blue or black fruits develop in spring and summer.
Taxonomy ''Berberis japonica'' was initially scientifically described and named by Carl Peter Thunberg as ''Ilex japonica'' in 1784, believing it to be a true holly. In 1821 Augustin Pyramus de Candolle reclassified it as ''Mahonia japonica''. Disagreeing with this, Kurt Polycarp Joachim Sprengel clasified it in ''Berberis'' as ''Berberis japonica'' in 1825.A paper was published by Joseph Edward Laferrière in 1997 summarized the arguments for ''Mahonia'' being more properly classified as a synonym of ''Berberis''. As of 2023 this is the most common classification by botanists.
Cultivation The plant is much grown as an ornamental shrub, and for use in landscapes. It is of value for its bold foliage, flowers in flowering season, and as a groundcover landscape shrub. Its spiny foliage invite use in security hedging. ''Berberis japonica'' has received the Royal Horticultural Society's Award of Garden Merit. The hybrid between it and ''Berberis oiwakensis'' subsp. ''lomariifolia'' is also a popular garden plant. Known as ''Berberis'' × ''hortensis'', several cultivars have been developed from it, including 'Charity', 'Winter Sun' and 'Lionel Fortescue'. A hybrid with ''Berberis napaulensis'' var. ''napaulensis'' (''M. siamensis''), called ''Mahonia'' × ''lindsayae'' 'Cantab', though less well known, is a useful garden plant and also holds an Award of Garden Merit. ''Berberis bealei,'' native to mainland China and also widely cultivated, is usually treated as a separate species, but in the past has been listed as a cultivar of ''Berberis japonica''. Its most obvious differences from ''B. japonica'' are in shorter, upright flowering racemes and wider leaflets.
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