Photosynthesis

Plants eat air: via photosynthesis they are able to extract carbon dioxide (CO2) from the air.
They snatch the carbon atom from the carbon dioxide molecule consisting of one carbon and two oxygen atoms, and use it to build organic molecules like sugar. This process needs a lot of energy, which is harvested from sunlight with the help of the green leaf-pigment chlorophyll.

To get as much energy as possible from the sun the positioning of the leaves is crucial. In the botanical garden this can be seen with the solar-panel.

For solar-panels and plants alike the area and the angle facing the sun is crucial for the amount of energy they are able to collect. All plant and all animal life on earth is based on this power of photosynthesis.