- Name also: European Crab Apple, European Apple, Wild Apple
- Family: Rose Family – Rosaceae
- Growing form and height: Thorny tree or broad shrub. 3–8 m (10–25 ft.).
- Flower: Regular (actinomorphic), large, fragrant. Calyx-lobes five, narrow-triangular, sharp-pointed, hairy in the inner surface. Petals five, inside white, outside pink, with rounded tip. Carpels three to five, fused. Inflorescence an umbel-like cluster of two to six flowers.
- Leaves: Borne on thorn-tipped short shoots. Long-stalked, hairless or sometimes hairy when young, blade 3–8 cm (1.2–3.1 in.), ovate with a tapering tip, toothed.
- Buds: Egg-shaped, red-green, shiny glabrous. Scale edges short-haired.
- Fruit: Small, 1–2 cm (0.4–0.8 in.), sour, green pome. Dark brown and glossy, oval, flattened seeds within a capsule surrounded by the enlarged, fleshy receptacle.
- Habitat: Dry or dryish, rocky broadleaf woods especially on slopes. Waterside thickets, coppices. Often on calcareous soils (calciphile).
- Flowering time: May–June.
- Endangerment: Vulnerable, protected in all of Finland except the Åland Islands.
Crab apple is quite small, dense-crowned, thorny tree or shrub. It is rare in Finland except in the Åland Islands, and it is difficult to tell apart from an escaped cultivated apple. The annual shoots, buds, and leaves of the crab apple are hairless, contrary to the cultivated apple. In addition, the flowers of the former are smaller, the petals narrower, and the petiole notably long compared to the lamina.
The apples (Malus spp.) are a genus of approx. 35 species most of which native to the temperate regions of North America, Asia, and Europe. They are typically cross-pollinated, many cultivars being self-sterile. When fruits are ripe (apples are eatable), cultivated trees are easy to tell apart from crab apple by the size of fruits. When apples are not ripe a closer look at leaves shows differences; crab apple’s leaves are glabrous and long-stalked (1,5–3 cm), cultivated apple’s hairy (at least under side) and shorter-stalked (1–2 cm). In addition crab apples are thorny. All together there are 10 000 apple cultivars , that means differences also in outlooks.