Green leaves are so because chlorophyll, the key compound in photosynthesis, absorbs all but the green light of the spectrum, which is reflected and seen by us as a green leaf. So then why are some leaves purple?Purple leaves are usually caused by a pigment called anthocyanin. There are a few reasons a plant would like a set of purple leaves — new leaves and seedlings often have red-purple leaves to help protect them from sun damage. The leaves of many tropical understorey plants have purple undersides. The collection of tropical plants in the Dunedin Botanic Garden’s Winter Garden Glasshouse has some great examples of these purple-leaved stunners.
Source: Otago Daily Times December 07, 2017 16:07 UTC