"Calcium is an extremely important plant nutrient due to its many functions, which includes membrane structural integrity, maintenance of homeostasis, segregation of genetic material during cell division, gene expression, energetics and enzyme activities. The full picture of calcium-mediated physiological processes has not been fully described here nor clarified in academic research; however, researchers do know that calcium is immobile in plants and that it is a constant requirement throughout all growth phases."
Within the world of Permaculture we often find reference to plants known as Dynamic Accumulators. In brief, this is the idea that certain plants (often deep-rooted ones) will draw up nutrients from the lower layers of the soil, and these nutrients will be stored in the plants’ leaves. When the leaves fall in autumn and winter and are broken down, those stored nutrients are then incorporated into the upper layers of the soil where other plants will benefit from their deposition.