The olive tree, Olea europaea, is an evergreen tree or shrub native to the Mediterranean, Asia and Africa. It is short and squat, and rarely exceeds 8–15 m in height. However, the Pisciottana, a unique variety comprising 40,000 trees found only in the area around Pisciotta in the Campania region of southern Italy often exceeds this, with correspondingly large trunk diameters. The silvery green leaves are oblong, measuring 4–10 cm long and 1–3 cm wide. The trunk is typically gnarled and twisted.
The small white, feathery flowers, with ten-cleft calyx and corolla, two stamens and bifid stigma, are borne generally on the previous year’s wood, in racemes springing from the axils of the leaves.
The fruit is a small drupe 1–2.5 cm long, thinner-fleshed and smaller in wild plants than in orchard cultivars. Olives are harvested in the green to purple stage. Canned black olives may contain chemicals (usually ferrous sulfate) that artificially turn them black. Olea europaea contains a seed commonly referred to in American English as a pit or a rock, and in British English as a stone.