What happens to the components of a leaf that a tree is about to shed?

1. In many trees the older leaves turn yellow and eventually fall. 2. Leaf fall is triggered by factors such as reduced photosynthetic efficiency under shading, or oxidative damage from photosynthetic reactions. 3. Before the leaf goes, its components are recycled by the plant for use in other processes. 4. Those processes include the development of seed and storage, and the whole business is called nutrient recycling. 5. Losing the components to the soil would waste them, which is precisely what recycling avoids. 6. The complex pathways of nutrient recycling within a plant are not well understood, though hormones are known to play a role in senescence. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 32 "Plant Reproduction", section 32.3 Asexual Reproduction_