When I look out into the sunshine on Dec. 21, the winter solstice (aka the longest night, shortest day) I will acknowledge two emotions. I understand the elation, relief and general drunken and gluttonous behaviors of some ancient peoples as they celebrated, no doubt with relief, the turning of the sun, which even as winter started, held the promise of spring.

My other emotion, thinking about plants, is absolute wonder at the process of photosynthesis and the fumbling early study of it that has led to new areas of cutting research and a number of Nobel prizes.

In the 1600s a Belgian chemist, Jan Baptista van Helmont "studied" willow twigs in a somewhat controlled environment for five years and "discovered" that water is important to the growth of plants.

We might say something as unkind as duh, but study by observation was providing information and provoking curiosity. In the 1700s, the English polymath Joseph Priestly, fascinated by gases, almost discovered oxygen. He played around with candles and mice in bell jars and discovered that plants could restore the (oxygenated) condition of the air for the candles and critters.

The Dutch physician Jan Ingenhousz deepened understanding of the photosynthetic process in 1770 when he demonstrated that plants use light to produce oxygen. In 1796, Swiss botanist, pastor and naturalist Jean Senebier demonstrated that plants absorb carbon dioxide and release oxygen in the presence of sunlight. In the 1880s, Nicholas Saussure, a Swiss chemist and plant physiologist, demonstrated that water is required (Remember Helmont 100 years earlier).

When the German physician and physicist Julius Robert von Mayer suggested in 1845 that photosynthetic organisms convert light energy into chemical-free energy, research took on a serious intent and by the middle 1800s people understood that plants used light energy to make carbohydrates from carbon dioxide and water but the full chemical understanding of the process was still a goal.

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Free energy is defined at its most simple as a thermodynamic quantity equivalent to the capacity of a system to do work. That wildly excites researchers in physics, biophysics, chemistry, molecular biology, biochemistry, structural biology and more and leaves most gardeners bewildered and out in the weeds.

But rather than grumble that the winter is long and miserable and garden-deprived, give some thought to the plants and other organisms that photosynthesize beautifully and — here’s the best part — still baffle science. Give a hand to the algae, the cyanobacteria, the purple bacteria, the green sulphur bacteria and the heliobacteria.

While we are handing out recognition, let’s include the greening and growing tips of our potted-for-the-holidays amaryllis and the greening stems of the papperwhite narcissus. Who says we have to understand photosynthesis with all of its six-carbon sugars and electronic transfers and free energy and CO2?

Let’s simply be grateful that the plants have worked out a congenial relationship with sunlight and colored our world green while my personal free energy suggests that a good book and a cup of tea are the perfect response to winter.

Cathie Draine is a South Dakota Cooperative Extension Master Gardener and a member of the Garden Writers Association. She lives and gardens in Whispering Pines. Contact her at blackhillsgarden.com.

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