Frond in autumn colours, Gros Morne National Park, Newfoundland

Frond in autumn colours, Gros Morne National Park, Newfoundland

It’s the season for pumpkins, apples, and fall colours–as demonstrated by the ferns in this image. We have science to thank for the influx of red, orange, and yellow colours in autumn. Trees change colour because of a chemical process in their leaves, primarily the breakdown of the green chlorophyll that allows plants to absorb energy from light. As the temperature drops and days get shorter, the tree’s food-making process slows down. Orange and yellow pigments–normally masked by chlorophyll – are dramatically revealed. Still other chemical processes produce those gorgeous red and purple hues, but the colours are fleeting, and usually mean it’s time to rake.