Basic Botany is a useful Tool for any Gardener
by Glenn Palmer
To me one of the important rewards of gardening has been gaining an appreciation for nature’s ingenuity, an understanding of the mechanisms that plants have adopted to carry them through their life cycles.
For example, take peas. The vine needs to fasten itself to the trellis for support as it climbs. But did you ever wonder how tendrils find the trellis? And what makes them twirl around? Or why do they climb in the first place?
Photo by Maria Keays
It’s all due to “isms” like phototropism. If the light is overhead when a seed sprouts it will grow toward the light. If the light is off to one side a hormone called auxin causes the cell on the side away from the light to grow faster, bending the stem toward the light source. That’s called positive phototropism. Growing toward the light.
Thigmotropism is growth in response to touch or contact. As the pea climbs, its tip spirals around and then when it contacts something that might serve as a support thigmotropism – a sense of touch – takes over and one-sided growth shifts to make the tendril wrap about that support.
Positive or negative geotropisms cause parts of plants to grow against or toward gravity, away from or toward the earth. Negative geotropism causes White Pines to grow straight up, away from gravity while Sourwoods stick with positive phototropism and wander back and forth seeking the sunlight as the canopy above them changes. That’s why pioneers used naturally bent Sourwood logs as sledge runners.
And then there’s sex. Not an “ism” but something a gardener needs to understand. How do plants reproduce? We cut and plant pieces of a potato – actually they’re pieces of the root – to grow a new plant and more potatoes. But that’s not nature’s way. Given the right conditions – long days and cool nights – potatoes, members of the same genus as tomatoes, will produce small flowers which develop into small green “berries”.
Photo by John Meade
Inside those berries will develop seeds which is the natural way for potatoes to reproduce. Due to our unusual 2015 weather pattern we’re seeing some of these potato berries in our gardens right now. But heads up! Those berries contain a toxin and are not edible!