Quercus robur, commonly known as the pedunculate oak or the English oak, is a species of tree in the family
Fagaceae, comprising
beeches and
oaks. It is a large
flowering plant, native to most of Europe, North Africa and western Asia. It is deciduous and grows to a height of up to 40 m (130 ft), with a single stout trunk that can exceed 10 m (33 ft) in girth. The fruits (
acorns) are borne in clusters of two or three, on a long peduncle (stalk) that is 4 to 8 cm (1.6 to 3.1 in) long. Each acorn is 1.5 to 4 cm (0.59 to 1.57 in) long, ovoid with a pointed tip, starting whitish-green and becoming brown, then black. As with all oaks, the acorns are carried in a distinctive shallow cup. It is an "alternate bearing" species, with large crops produced every other year. This photograph shows a pile of acorns, in various stages of ripening, taken from a
Q. robur tree near
Brastad, Sweden, and photographed on a plank of oak wood. The photograph was
focus-stacked from eight separate images.
Photograph credit: Ann-Sophie Qvarnström
