Flowers produce the energy they need to sustain life by means of photosynthesis. This biological process begins when the plant absorbs the sunlight that strikes its leaves. The plant uses that light to produce the carbohydrates on which it feeds.
The pigment chlorophyll, which is usually green (but sometimes brown), is abundant in the leaves of almost all kinds of plants. This pigment absorbs the sunlight that strikes the leaves and transfers the energy from the sunlight into the cells of the plant. That energy ultimately fuels the chemical reactions that produce food for the flower.
Chemical compounds are substances made up of different combinations of atoms. Two specific compounds have to be present for photosynthesis to take place. The first is water, which the plant absorbs through its roots. Water (H20) contains two atoms of hydrogen and one atom of oxygen. Carbon dioxide (CO2) contains one atom of carbon and two of oxygen.
Mixing It Up
The chemical reactions by which flowers create energy involve breaking the water molecules apart into its component hydrogen and oxygen atoms, breaking the carbon dioxide into carbon and oxygen atoms, and then combining all these components to create carbohydrates, which are long molecules comprised mostly of carbon. The flower feeds on the resulting carbohydrates, converting them into energy.
The process of photosynthesis doesn't use all the resulting free oxygen atoms, which naturally bond into pairs (O2). The plant then expels the excess oxygen back into the atmosphere. This is one reason why green plants are beneficial to life on earth---they absorb, or inhale, carbon dioxide and release, or exhale, oxygen, which other living things need to survive.