Leaves look green because chlorophyll inside them absorbs red and blue light while reflecting green.

The longer version

Light reaching a leaf is a mixture of wavelengths. Chlorophyll molecules sit inside chloroplasts and absorb strongly in the red and blue parts of the spectrum, using that energy to drive the reactions that build sugar. Green wavelengths are absorbed far less, so they bounce back to the eye.

The shade of green also depends on how much pigment is packed into the cells. A leaf with dense chlorophyll looks darker than a pale young one, and differences between species reflect how each balances light capture against the risk of damage from excess sun. Changes in colour can therefore reveal stress, since a plant sheds pigment when light or nutrients run short.

Where this entry sits

Plants and Trees gathers ordinary and surprising details about how green things live, from the tallest forest giants down to the moss on a garden wall. Expect notes on flowers, seeds, roots, leaves, fungi, and the quiet tricks plants use to spread and survive. The full list sits on the Plants and Trees page, where every entry is listed in order.