In bloom: Water, water everywhere
Special to The Aspen Times
Aspen, CO Colorado
NEW CASTLE, Colo. – During the height of the spring rains earlier this week, I found myself in a deluge just below the Flat Tops on the East Elk Creek Trail near New Castle. As I ran down the trail in a vain attempt to keep warm, shoes sloshing, so-called “waterproof” clothing glued to my skin, I tried to lift my spirits by thinking of how happy the rain was making the wildflowers.
Of course, the wildflowers don’t have any opinion as to the rain. They simply deal with whatever comes their way, be it heavy rain, or snow, or drought. But there is no doubt that water is the critical factor in a wildflower’s season. This is because plants need only three things for photosynthesis, which makes the food that fuels their growth – sunlight, carbon dioxide, and water – and the first two are generally abundant.
If the rains don’t come, wildflowers respond by slowing or stopping growth, which can include not producing flowers or letting them fall off. Since most of our wildflowers are perennials, meaning they live from year to year, producing flowers is optional in the sense that the parent plant will likely have opportunities to reproduce in summers to follow.
If, on the other hand, water is abundant, plants can grow taller and leafier with more flowers and therefore potentially more seeds for future generations. Evidence for this should come next week when the wildflowers explode throughout the Roaring Fork Valley in response to the rains.
Water does more, however, than just provide the crucial third ingredient for photosynthesis and growth. Water provides the very growth force itself – that is, the pressure that drives the expansion of stems and leaves.
Where does this pressure come from? It comes from the differing concentration of solutions on each side of the plant cell’s membranes. Water inside the cytoplasm of the plant’s cells is filled with large, dissolved molecules, while water outside the plant’s membranes in the soil contains smaller molecules. It is the disparity between these two solutions that generates pressure, because the system wants to be in equilibrium, a state where there are solutions of equal concentration on each side. Since the large molecules cannot move through the membrane out of the cell and into the soil, the only way for equilibrium to be reached is for water to move from the soil into the cell. The result is pressure.
It is this pressure, pushing against the cell’s walls, that enables cow parsnip to grow pizza-sized leaves, and monkshood to stand 6 feet tall on impossibly slender stems, stems made turgid with water. Remembering these things on a soggy hike can make the rain a bit easier to bear.