Berberis verruculosa aka Warted Barberry

Berberis verruculosa, or warty barberry, is an evergreen shrub. It belongs to the barberry family, Berberidaceae. Its native range includes Sichuan and southern Gansu in China. It grows in woods, thickets, and rocky ground. It forms a dense, rounded bush with arching branches. Most garden accounts give heights of 3–5 feet [0.9–1.5 metres]. NC State reports plants reaching 6 feet [1.8 metres]. Spread reaches about 5 feet [1.5 metres], according to RHS. Growth is slow, with maturity taking 10–20 years.

Small, raised bumps give the light brown stems their rough feel. These bumps also give the shrub its common name. Slender spines split into three points along the stems. The simple leaves grow in an alternate pattern. They cluster on short shoots near the spines. Each leaf has a tough, leathery feel and toothed edges. The upper face shines dark green; the underside looks white or silver. Leaves may turn purple-green or deep brown-red in winter. The shrub keeps its leaves through the year.

Yellow flowers open in late spring, sometimes lasting into summer. RHS describes single blooms about 0.8 inches across. Dark purple to blue-black berries follow in autumn. A pale, waxy coat covers their surface. The small fruits measure about 0.3–0.4 inches long. Birds spread the seeds, and plants can form thickets. Full sun gives the best flower and fruit display. The leaves, fruit, and arching stems provide interest across seasons.

This shrub grows in sun or partial shade. Oregon State also lists shade as a suitable site. It accepts clay, loam, sand, and chalk with good drainage. Acid, neutral, and alkaline soils all suit it. Moist soil suits cultivation, but established plants tolerate drought. RHS rates its UK hardiness as H5. NC State gives a USDA range of zones 5–10. It needs little upkeep and suits hedges, screens, or single plantings. It also suits coastal gardens, banks, and slopes. Dense growth can form a barrier and help limit erosion. Plants tolerate trimming, though PFAF favours leaving them untrimmed.

Aphids and barberry sawfly may attack the shrub. Powdery mildew and honey fungus are possible disease problems. NC State lists resistance to deer and rabbits. PFAF reports a yellow dye from the roots. It also lists raw or cooked fruit as edible but poor. RHS warns against eating the fruit and flags risks to pets. NC State identifies bark as poisonous, with low-severity effects. Swallowing toxic parts can cause nausea, vomiting, and diarrhoea. These conflicting food reports do not support treating it as safe.