Crying Chestnut Branch

A freshly cut chestnut branch (aesculus hippocastanum) is submerged in the darkness into a 1 L beaker that has been filled with water. Under irradiation with violet light (λ = 400 nm) or UV-light (λ = 365 nm) from an LED flashlight, it is possible to see how a blue-whitish glowing substance, esculin, flows from the incision out of the branch and mixes with the water. The luminescent substance (the fluorescence) is invisible under daylight.

A short video showing a blue-white glowing substance, esculin, flowing out of the incision into a chestnut branch under irradiation with UV light (λ = 365 nm). The substance spreads within the water.