Corylus Avellana - Description, Ecology and Nomenclature

Description, Ecology and Nomenclature

Common hazel is typically a shrub reaching 3–8 m tall, but can reach 15 m. The leaves are deciduous, rounded, 6–12 cm long and across, softly hairy on both surfaces, and with a double-serrate margin. The flowers are produced very early in spring, before the leaves, and are monoecious with single-sex wind-pollinated catkins. Male catkins are pale yellow and 5–12 cm long, while female catkins are very small and largely concealed in the buds with only the bright red 1–3 mm long styles visible. The fruit is a nut, produced in clusters of one to five together, each nut held in a short leafy involucre ("husk") which encloses about three quarters of the nut. The nut is roughly spherical to oval, 15–20 mm long and 12–20 mm broad (larger, up to 25 mm long, in some cultivated selections), yellow-brown with a pale scar at the base. The nut falls out of the involucre when ripe, about 7–8 months after pollination.

It is readily distinguished from the closely related filbert (Corylus maxima) by the short involucre; in the filbert the nut is fully enclosed by a beak-like involucre longer than the nut.

The leaves provide food for many animals, including Lepidoptera such as the case-bearer moth, Coleophora anatipennella. Caterpillars of the concealer moth, Alabonia geoffrella, have been found feeding inside dead common hazel twigs. See also List of Lepidoptera that feed on hazels.

The fruit are possibly even more important animal food, both for invertebrates adapted to circumvent the shell (usually by ovipositing in the female flowers, which also gives protection to the offspring) and for vertebrates which manage to crack them open (such as squirrels and corvids).

The scientific name avellana derives from the town of Avella in Italy, and was selected by Linnaeus from Leonhart Fuchs's De historia stirpium commentarii insignes (1542), where the species was described as "Avellana nux sylvestris" ("wild nut of Avella").