Each leaf has a pattern of veins as distinctive as fingerprints. These constantly bring a supply of water upwards from the roots, to be ultimately lost through pores (stomata) in the leaf surface. A full-sized oak tree can lose several tones of water by transpiration every day.
These leaves were photographed on a light-pad and then given a blue-brown gradient.
Stan Farrow FRPS EFIAP DPAGB