Phenological phases

British oak (Quercus robur L.)

Leaf unfolding

Closed buds

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The defined stage of leaf appearance

The buds have flushed and the green of the new leaves are clearly visible.

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After the defined stages of leaf appearance

The new leaves are unfolded and the leaf blade is fully visible.

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Photos: Eija Matikainen


The flowers of male (staminate) inflorescence (hanging catkins) are open and begin to release yellow pollen. (On windy days the release of pollen is visible).

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Photos: Eija Matikainen / Erwin Ulrich

Lammas shoots


Photo: Erwin Ulrich

Autumn colouring

Leaves have changed their colour from green to yellow, yellow-brown, orange-brown or brown. Often single leaves are only partly autumn coloured. The estimation of autumn colouring refers to the whole leaf area of the tree, including the leaves that have already fallen down during the colouring period, relative to the state before colouring starts.

Begining of autumn colouring

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Photos: Egbert Beuker

Autumn colouring


Photo: Astrid Vasella