Buxus is a genus of about 70 species in the family Buxaceae. Common names include boxwood (North America) and box (all other English-speaking countries).
The boxes are native to western and southern Europe, southwest, southern and eastern Asia, Africa, Madagascar, northernmost South America, Central America, Mexico and the Caribbean, with the majority of species tropical or subtropical; only the European and some Asian species are frost-tolerant. Centres of diversity occur in Cuba (about 30 species), China (17 species) and Madagascar (nine species).
They are slow-growing evergreen shrubs and small trees, growing to 2–12 m (rarely 15 m) tall. The leaves are opposite, rounded to lanceolate, and leathery; they are small in most species, typically 1.5–5 cm long and 0.3-2.5 cm broad, but up to 11 cm long and 5 cm broad in B. macrocarpa. The flowers are small and yellow-green, monoecious with both sexes present on a plant. The fruit is a small capsule 0.5-1.5 cm long (to 3 cm in B. macrocarpa), containing several small seeds.
The genus splits into three genetically distinct sections, each section in a different region, with the Eurasian species in one section, the African (except northwest Africa) and Madagascan species in the second, and the American species in the third. The African and American sections are genetically closer to each other than to the Eurasian section (Balthazar et al., 2000).
Culture and Use
Boxes are commonly used for hedges and topiaries, and the dense wood is valued for wood carving and the making of wood type for printing. The inconspicuous flowers mean that boxes are usually only grown for their foliage.
Given time, neat low hedging can grow to enormous size, as at Powis Castle in north Wales. Often, however, they are kept dwarfed, as in the famous gardens at Château Villandry in France.
Boxwoods can be sensitive to sun, dry and wet soils, and exposure to winter winds. Deep, well-drained, humus-rich soils are the preferred conditions.
Boxwoods can be difficult to grow because they are prone to serious pest and disease problems, so careful monitoring for signs and symptoms is a must.
Pests, Diseases, and other Problems
Curled leaves -- Boxwood Psyllid
Stippling -- Mites
Bronzing -- Winter damage, Volutella blights, Phytophthora
Balthazar, M. von, Peter K. Endress, P. K., and Qiu, Y.-L. 2000. Phylogenetic relationships in Buxaceae based on nuclear internal transcribed spacers and plastid ndhF sequences. Int. J. Plant Sci. 161(5): 785–792 (available online).