Research tells us that plants “know” a lot more about what’s going on than we think they do. In his 2012 Scientific American book What a Plant Knows, renowned biologist Dr. Daniel Chamovitz suggests that plants can sense and communicate in surprising ways. In recent decades, he and fellow university researchers have studied how plants experience the physical world. They tracked plants’ responses to light, lack of water, pest attacks, scents and even sound. They discovered evidence at the cellular level that shows that, while plants do not have brains, they do have receptors that allow them to sense insect predators, produce chemicals to defend themselves, warn neighboring plants of drought, detect the scent of ripening fruit and more.
The fact that plants have a type of intelligence won’t surprise most gardeners, who have long known that plants can be plenty smart. In fact, if Dr. Chamovitz and other researchers are interested, gardeners can even tell them which plants are the smartest.
Weeds, of course!
The evidence that weeds may be smarter than the average vegetation is abundant. Weeds exhibit an amazing number of creative techniques to, effectively, outfox those who would do them in.
Weeds are able to determine when mid-summer arrives – plants can track the hours of daylight. Evidence is strong that weeds sense that this is the time to get aggressive.
“At this time of year, the late season weeds get busy producing seeds, and I mean lots and lots of seeds,” says Maryanne Bayoumy of Lebanon Seaboard, producer of Preen garden weed preventer, a pre-emergent that stops weed seeds from growing for up to three to four months per application. “Applying Preen in spring stops early season weeds. Now it’s time to stop the seeds of these aggressive late season weeds from germinating.”
In mid-summer, summer annual weeds such as pigweed, common lambsquarters, crabgrass and galinsoga, start distributing a new crop of seeds in most parts of the country. And a staggering amount of seeds it is. A single pigweed plant can produce more than 100,000 seeds. Lambsquarters produces about 75,000 seeds per plant, seeds that remain viable for decades, ready to germinate when exposed to light. Other types of weeds have similar strategies.
Of course there’s no real evidence that weeds have higher IQs than petunias and other plants, but they sure can be persistent. In the end, the best way to outsmart smartypants garden weeds is to show them how smart you are instead. Stop them before they ever start growing. Stop them when they are still seeds.
Editor’s note: What A Plant Knows is scientifically-sound and a very good read. For those who recall “an extremely popular but scientifically anemic” 1970s book, Dr. Chamovitz says: “My book is not The Secret Life of Plants; if you're looking for an argument that plants are just like us, you won’t find it here. …Instead, in each chapter I highlight a human sense and compare what the sense is for people and what it is for plants. I describe how the sensory information is perceived, how it is processed, and the ecological implications of the sense for a plant.”