Zelkova Spach (1841), in the family Ulmaceae, contains 4 species from Europe and Asia.

Description Trees to 40m, or shrubs, with smooth and sometimes flaky bark. The leaves are alternate, deciduous, rough, often with coarse, blunt teeth, with pinnate veins, nearly symmetric at the base. The flowers are small, unisexual, appearing as the leaves unfurl. The males are in bunches at the base of the twigs, the females single in the leaf axils towards the tips. Sepals 4 or 5; petals absent. Stamens 4 or 5. Carpel 1, with a deeply 2-lobed style. Pollination is by wind. The fruits are 1-seeded, green, stalkless, and slightly fleshy.

Key Recognition Features The rough, coarsely toothed leaves, with pinnate veins, and the smooth bark, flaking in small pieces. Zelkova serrata Mak. and Z. carpinifolia (Pall.) K. Koch tend to have many tall, upright branches from a short, thick trunk.

Evolution and Relationships Zelkova is close to Ulmus in most characteristics, but the 1-seeded, fleshy fruit links it with Celtis.

Ecology and Geography In woods and on rocky hillsides, with Z. abelicea (Lam.) Boiss., syn. Z. cretica Spach, in Crete; Z. carpinifolia in northern Turkey and the Caucasus; Z. sinica Schneid. in China, and Z. serrata in Japan.

Comment All the species are planted as ornamentals. Zelkova serrata is susceptible to Dutch elm disease (see Ulmus), but the others are resistant. Zelkova carpinifolia is especially striking in its upright main branches, and Z. abelicea is a particularly elegant small tree.