Down to Earth | October showers bring November flowers
- Published: December 5, 2024
By Don Cipollini
The severe drought we experienced in late summer this year has led to several interesting phenomena in the plant world.
When faced with stresses such as severe drought, plants are not passive bystanders. They trigger several adaptations that allow them to survive such stresses and to limit the amount of damage they incur. Some adaptations to drought include things we cannot see without looking carefully, such as increasing levels of a drought-stress hormone in leaves that helps plants conserve water and pausing growth of the shoots to prioritize growth of roots. Others could be readily observed during the height of the drought and include the intentional senescence and loss of a portion of their leaves. At first glance, this looks like damage, but instead, the plant intentionally sheds leaves to reduce surface area through which water loss can occur. This helps preserve the remaining leaves on the plant under conditions of limited water. When rains finally came, most of these leaves were shed and those that remained looked and functioned fairly normally thereafter.
A more recently observed phenomenon is the off-season flowering of several tree and shrub species that normally flower in the spring. In the Miami Valley, this could be observed on a number of non-native ornamental species, including lilacs, forsythias, crabapples and Callery pears. Normally, these plants develop floral buds in fall, then flower in the spring after a period of winter dormancy. The pause in growth that plants took this year during the drought served somewhat like a winter dormancy period for plants, and the couple of weeks we endured with cool temperatures in early fall reinforced it. When the rains returned, some plants came out of their drought-induced dormancy with a burst of flower production like they would in spring.
Unfortunately for the plant, these flowers will not survive to be fertilized and produce fruit before hard freezes come. In turn, the floral display on plants that flowered this fall will be less showy in the spring as they have “used up” many of their buds already, but the overall health of the tree will be unaffected.
The drought this year in the Miami Valley induced several interesting phenomena in the plant world, but, while severe, it will likely have little long-term effect on plants unless below-normal water levels persist.
*The author is a Yellow Springs resident and professor of plant biology and ecology at Wright State University.
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