What’s Up with the Stupid Magnolias?
In late September, I saw several magnolia trees blooming in Durant, Oklahoma. Magnolias are supposed to bloom in late spring! What’s up with that?
The reason the magnolias bloomed is because they are stupid. Plants are stupid. I say this even though I am a botanist and have devoted my life to studying them. These magnolias, you see, have no idea what time of year it is. They don’t know the difference between May and September.
Yet, they have to bloom at the right time of year, don’t they? Of course they do. They have to bloom at the time that their pollinators are expecting them to bloom, so that the huge white flowers and sultry lemon scent will not be wasted.
But intelligence is expensive. Brains are expensive. Your brain uses twenty percent of your body’s metabolic energy and oxygen. My granddaughter Léna’s brain uses half of her energy and oxygen. That doesn’t make her smarter than you, but it does mean her brain is rapidly growing. Plants simply cannot afford to make brains. For the last billion years, plants and their evolutionary ancestors have relied on more direct stimuli from the environment to tell them when to do things such as reproduce.
To a plant, there is no difference between cold and drought. They do not have temperature sensors. To them, it is cold when the water freezes, and when the water freezes, it diffuses out of the cells and into intercellular spaces, where the ice crystals cannot harm the cell. That is, when it freezes, plant cells become drier. In spring the ice melts and the water diffuses back into the cells.
This summer in Oklahoma had some long periods of hot dry conditions. They were not record-setting, but they were pretty brutal. Then, in late summer and early fall, it rained a lot, and kept raining. Therefore, during mid-summer, the plant cells dried out, and in late summer, they became moist. For anything that the plant knew to the contrary, the summer drought was winter, and the fall rains were spring.
Plant responses to seasons are not the most intelligent ones, but they are economical. Every few years, the magnolia trees waste a few flowers by blooming in the fall; in the ensuing winter, they cannot develop their fruits. But any magnolia would tell you that its way of adjusting to the seasons doesn’t cost as much as your brain does, thank you very much.