Tell me about plant life cycle
Like any living being, a plant is programmed for its specie to last over generations.
With winter coming, the plant will generate seeds, what is called « fructification ». 
These seeds are basically a strong capsule containing the plant’s genetic material and enough energy for the germ to grow the first leaf which will start photosynthesis.
The energy contained in the seed is stabilised under the form of starch. It is basically a long chain of sugar polymerised.
During winter, the seed hibernate, but when spring comes, specific weather conditions (humidity, temperature) degrade the starch and release elementary sugar molecules for the new growing plant to create its first leaf.
Chlorophyll contained in leaves will enable the plant to produce its own energy; glucose sugar, from carbon dioxyde, water and light, and continue to grow, until the next cycle.
There is a bit of magic with plants: creating oxygen and energy from air and sun!