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Word of the Week: Anthocyanin

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Welcome to Word of the Week! Stay tuned for a new word each week to amp up your nature vocabulary!

The word of the week is anthocyanin [an-thow-sai-uh-nin] (noun): pigments responsible for the blue, violet or red colouring in flowers and plants.

The red maple leaf in the Canadian flag is universally recognized as the symbol for Canada, but do you know what’s responsible for the red coloration in the fall foliage of maple leaves?

After photosynthesis stops, glucose ends up being trapped in the leaves of some trees like the maple tree. The shorter duration of sunlight coupled with the cooler temperatures at night causes this trapped glucose to turn into a red pigment that has anthocyanins, which is responsible for the red colours in the leaves of trees like maples and oaks and the fruits of plants like sumacs.

Once the chlorophyll, responsible for the green colour of leaves, degrades, the yellowish pigment of carotenoids which are present in the leaves year-round become more visible. Unlike carotenoids, however, anthocyanins are only produced in the fall in the leaves of some plants due to complex external and internal factors affecting the leaves. Orange leaves are due to a combination of anthocyanins and carotenoids.