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Archive for September 26, 2011

Anthocyanins

Red maple leaves can already be seen scattered on the forest floor.  Their red color, as well as the purples of autumn foliage, come  from a group of pigments called anthocyanins.  Unlike carotenoids, pigments which produce yellows and oranges and are present in leaves year round, anthocyanins are produced towards the end of summer.  At this time phosphate, which has been helping break down the sugar that the plant has made during the warmer months, begins to decrease in the leaf, and this triggers the production of anthocyanin pigments.  The amount of anthocyanin produced is, in part, determined by the weather — cool and sunny days, and cold, but not freezing, nights all but guarantee brilliant foliage. Let’s hope the temperature drops a bit in the near future!