The “fruit” of the London plane tree is actually a dense, ball-shaped cluster of individual fruits. These hang on long stalks, often in pairs, from the tree’s branches.
Fruit of the London plane tree [photograph https://commons.wikimedia.org/wiki/User:Alvesgaspar]The individual fruits are called achenes. Each achene contains a single seed. Attached to the base of each achene is a tuft of many thin, stiff, yellow-brown fibres. These fibres help the wind disperse the achenes to new locations.
The individual fruits (achenes) of the London plane tree, showing the dense fibres. [Photograph: https://commons.wikimedia.org/wiki/User: Jebulon ]The achene cluster breaks up slowly over the winter, releasing the individual achenes (each containing a single seed) to be dispersed by wind.
When the conditions are right, the seed germinates, breaking through the achene, growing roots into the soil.
Fruits that are dispersed by animals (like the blackberry) are often brightly coloured, juicy and sweet tasting. Those fruits that are dispersed by the wind are often dry, small and lightweight. Why do you think this is?
