I'm thinking my grade school music teacher must have been Irish, because at the beginning of every March we learned the lilting songs of Ireland in preparation for St. Patrick's Day.
But it wasn't until I became mildly obsessed with historical fiction that I learned that "The Wearing of the Green" began as a protest song — born in a dark period of Irish history, when people were punished simply for displaying Irish identity.
Today, like Halloween or Christmas, St. Patrick's Day has become a broadly secular celebration. The festivities often begin well before March 17th. This weekend, plenty of people will be wearing green.
But I'm not quite ready for the wearing of the green — and neither are many of our plants.
Step outside in early spring and you'll notice that many so-called green plants are tinged with red or purple. That color comes from anthocyanin — a pigment that acts like a built-in sunscreen, shielding delicate young leaves from excess light, especially ultraviolet radiation.
Because here's the challenge: early spring sunlight can be bright, even when the air is cold. And cold leaves can't process light energy efficiently. When that happens, too much light can actually damage plant tissues.
Anthocyanin helps prevent that damage. At the same time, it absorbs red wavelengths that can slightly warm the leaf — sometimes just enough to speed growth or reduce the risk of freezing on a chilly morning.
As the season progresses and temperatures rise, chlorophyll production increases. Leaves turn fully green and operate at full photosynthetic capacity, using mostly blue and red light for energy while reflecting much of the green light we see.
But in those first bright, cold weeks of spring, young leaves are thin enough that even some green light — usually reflected — can slip inside and help power photosynthesis.
Nature, it turns out, doesn't rush the wearing of the green.
