Shrubs or subshrubs, evergreen or deciduous, 0.1-4.5(-8) m, glabrous or with tomentose stems. Rhizomes present or absent, short or long, not nodose. Stems branched or unbranched, monomorphic or dimorphic, i.e., all elongate or with elongate primary stems and short axillary spur shoots. Leaves alternate, sometimes leaves of elongate shoots reduced to spines and foliage leaves borne only on short shoots; foliage leaves simple or 1-odd-pinnately compound; petioles usually present. Simple leaves: blade narrowly elliptic, oblanceolate, or obovate, 1.2-7.5 cm. Compound leaves: rachis, when present, with or without swollen articulations; leaflet blades lanceolate to orbiculate, margins entire, toothed, spinose, or spinose-lobed; venation pinnate or leaflets 3-6-veined from base. Inflorescences terminal, usually racemes, rarely umbels or flowers solitary. Flowers 3-merous, 3-8 mm; bracteoles caducous, 3, scalelike; sepals falling immediately after anthesis, 6, yellow; petals 6, yellow, nectariferous; stamens 6; anthers dehiscing by valves; pollen exine punctate; ovary symmetrically club-shaped; placentation subbasal; style central. Fruits berries, spheric to cylindric-ovoid or ellipsoid, usually juicy, sometimes dry, at maturity. Seeds 1-10, tan to red-brown or black; aril absent. x = 14.
Species ca. 500 (22 in the flora).
Many species of Berberis are grown as ornamental shrubs. Some species harbor the black stem-rust of wheat (Puccinia graminis Persoon); the sale or transport of susceptible or untested species is illegal in the United States and Canada. Data on susceptibility of Berberis spp. to infection by Puccinia graminis was supplied by Dr. D. L. Long, U.S. Department of Agriculture (pers. comm.).
The berries of many species are edible and frequently are used for jam and jelly.
The genus Berberis as recognized below is divided into two genera, Berberis and Mahonia, by some authors (e.g., L. Abrams 1934). Species 1-5 below represent Berberis in the narrow sense (characterized by dimorphic stems, with elongate primary stems and short axillary shoots; leaves of primary stems modified as spines; foliage leaves simple; and inflorescences usually rather lax, with acuminate bracteoles and 1-20 flowers; most species susceptible to Puccinia). Species 13-22 represent the segregate genus Mahonia (with stems never regularly dimorphic; stem spines absent; leaves pinnately compound; and inflorescences dense, with rounded or obtuse [rarely acute] bracteoles and 25-70 flowers; never susceptible to Puccinia). Species 6-12, traditionally included in Mahonia when that genus is recognized (L. Abrams 1934), are actually intermediate, resembling Berberis proper in their dimorphic stems, inflorescence structure, and susceptibility to Puccinia, and Mahonia in their spineless stems and compound leaves. Species showing different combinations of the characteristics of the two groups are found in other parts of the world (J. W. McCain and J. F. Hennen 1982; R. V. Moran 1982), so these segregate genera do not seem to be natural. Mahonia is often recognized in horticultural works, but it is seldom recognized by botanists.
McCain, J. W. and J. F. Hennen. 1982. Is the taxonomy of Berberis and Mahonia (Berberidaceae) supported by their rust pathogens Cumminsiella santa sp. nov. and other Cumminsiella species (Uredinales)? Syst. Bot. 7: 48-59.
|1||Stems spiny; leaves simple; plants deciduous or evergreen.||> 2|
|1||Stems not spiny; leaves compound; plants evergreen.||> 6|
|2||Plants evergreen; leaf blades thick and rigid, each margin with 2-4 teeth or shallow lobes, each tooth or lobe 1-3 mm, tipped with spine 1.2-1.6 × 0.2-0.3 mm; stems tomentose.||Berberis darwinii|
|2||Plants deciduous; leaf blades thin and flexible, margins entire or each with 3-30 teeth, each tooth 0-1 mm, tipped with bristle 0.2-1.4 × 0.1-0.2 mm; stems glabrous.||> 3|
|3||Inflorescences of solitary flowers or umbellate; margins of leaf blade entire.||Berberis thunbergii|
|3||Inflorescences racemose; margins of leaf blade entire or toothed.||> 4|
|4||Bark of 2d-year branches gray; each margin of leaf blade with (8-)16-30 teeth; racemes 10-20-flowered.||Berberis vulgaris|
|4||Bark of 2d-year branches brown, purple, or reddish; leaf blade entire or each margin with 3-12 teeth; racemes 3-15-flowered.||> 5|
|5||Leaf blade oblanceolate or sometimes narrowly elliptic, apex rounded or rounded-obtuse; surfaces adaxially ± glaucous.||Berberis canadensis|
|5||Leaf blade narrowly elliptic, apex acute to obtuse or rounded; surfaces adaxially not glaucous, often shiny.||Berberis fendleri|
|6||Racemes loose (rather dense in B. harrisoniana), 1-11-flowered; bracteoles acuminate.||> 7|
|6||Racemes dense, 25-70-flowered; bracteoles obtuse or acute.||> 13|
|7||All leaves 3-foliolate; terminal leaflet sessile.||> 8|
|7||Leaves 5-11-foliolate (sometimes a minority of leaves 3-foliolate); terminal leaflet stalked on most or all leaves.||> 9|
|8||Terminal leaflet blade 0.9-2 cm wide; berries red.||Berberis trifoliolata|
|8||Terminal leaflet blade 2.2-3.2 cm wide; berries blue-black.||Berberis harrisoniana|
|9||Marginal spines of leaflet blade 0.4-1.2 × 0.1-0.15 mm.||> 10|
|9||Marginal spines of leaflet blade 0.8-3 × 0.2-0.3 mm.||> 11|
|10||Bracteoles (at least proximal ones) leathery, spine-tipped; berries white or red, somewhat glaucous, 9-16 mm, usually hollow; c Texas.||Berberis swaseyi|
|10||Bractoles usually membranous, seldom spine-tipped; berries yellowish red to red, not glaucous, 5-6 mm, solid; s California.||Berberis nevinii|
|11||Berries dry, inflated, 12-18 mm.||Berberis fremontii|
|11||Berries juicy, solid, 5-8 mm.||> 12|
|12||Blade of terminal leaflet mostly 2-5 times as long as wide; berries purplish red.||Berberis haematocarpa|
|12||Blade of terminal leaflet mostly 1-2.5 times as long as wide; berries yellowish red.||Berberis higginsiae|
|13||Bud scales persistent, 11-44 mm; leaflet blades 4-6-veined from base; anther filaments unappendaged.||> 14|
|13||Bud scales 2-8(-14) mm, deciduous; leaflet blades 1-3-veined from base (sometimes 1-5-veined in B. amplectens); distal end of each anther filament with pair of recurved teeth (status of this character in B. amplectens unknown).||> 15|
|14||Shrubs 0.1-0.8(-2) m; teeth 6-13 per blade margin, 1-2(-3) mm, spines 0.1-0.2 mm thick; native, Pacific Coast states, B.C., and Idaho.||Berberis nervosa|
|14||Shrubs 1-2 m; teeth 2-7 per blade margin, 3-8 mm, spines 0.3-0.6 mm thick; locally naturalized, se United States.||Berberis bealei|
|15||Leaflet blades abaxially smooth and somewhat shiny (outer surface of cells of abaxial epidermis of leaf plane).||> 16|
|15||Leaflet blades abaxially papillose and very dull (outer surface of cells of abaxial epidermis of leaf strongly bulging).||> 17|
|16||Blade of terminal leaflet 1.3-1.9 times as long as wide; lateral leaflet blades elliptic to ovate or broadly lanceolate.||Berberis pinnata|
|16||Blade of terminal leaflet 1.7-2.5 times as long as wide; lateral leaflet blades lance-ovate or lance-elliptic.||Berberis aquifolium|
|17||Leaflet blades thin and flexible; teeth 6-24 per blade margin, 0.1-0.25 mm thick; plants 0.02-0.2(-0.6) m.||Berberis repens|
|17||Leaflet blades thick and rigid; teeth 2-15 per blade margin, 0.2-0.6 mm thick; plants 0.3-2 m (0.1-0.4 m in B. pumila).||> 18|
|18||Leaflet blades adaxially glossy.||> 19|
|18||Leaflet blades adaxially dull, ± glaucous.||> 20|
|19||Teeth 6-12 per blade margin; n California and Oregon.||Berberis piperiana|
|19||Teeth 3-5 per blade margin; Arizona and New Mexico.||Berberis wilcoxii|
|20||Blade margins strongly crispate, each margin with 3-8 teeth.||Berberis dictyota|
|20||Blade margins plane to undulate or, if crispate, each margin with 9-15 teeth.||> 21|
|21||Plants 0.2-1.2 m; each blade margin with 9-15 teeth.||Berberis amplectens|
|21||Plants 0.1-0.4 m; each blade margin with 2-10 teeth.||Berberis pumila|