To give themselves an edge over their neighbors, many plants have evolved the ability to deploy chemicals, to make life a lot harder for other plants. That way, they can have more space and resources for themselves. This phenomenon is called allelopathy.
Hi, this is Iain MacLeod from New Hampshire Audubon, bringing you Something Wild.
For many of us, the sight of flower-filled gardens and lush, green forests evokes feelings of peace and tranquility. But for the plants themselves, it's often another story. Right before our eyes, there's a chemical warfare going on. It's a jungle out there.
Plants need to compete for water, sunlight and nutrients, and, like animals, for territory. To give themselves an edge over their neighbors, many plants have evolved the ability to deploy chemicals, to make life a lot harder for other plants. That way, they can have more space and resources for themselves.
This phenomenon is called allelopathy.
Many plants use this chemical warfare, including sunflowers, tobacco, rice and peas. Black walnut trees are particularly famous for their ability to prevent the growth of other plants.
Harmful chemicals can be present in any part of the plant. Competing plants are affected by these toxins in different ways. The toxins may inhibit the germination of seeds, growth or photosynthesis. Or they may block the absorption of critical nutrients. The affected plants will fail to thrive and may eventually die.
Plants release these chemicals in several ways. Some release toxic gases through small openings in their leaves. Others release compounds into the soil through their roots. Leeching is another method- for example, have you ever noticed that very few plants grow underneath pine trees? Pine needles contain acid that leeches into the soil when the needles decompose. This doesn't hurt the pine tree, but it inhibits the growth of other plants.
Allelopathy is really the ultimate in natural weed control. Researchers are even trying to develop crops that can defend themselves against common weeds. Just be careful about what you plant under that black walnut tree, because you are likely to be disappointed with the results.
Something Wild is a joint production of New Hampshire Audubon, New Hampshire Public Radio and Society for the Protection of New Hampshire Forests. For Something Wild, I'm Iain MacLeod.
