by Dorothy McGowan
People like plants for many reasons – some appreciate plants because they love that juicy tomato sandwich in summer and most of us don’t consciously think that if there were no plants there would be no animal and human life. We appreciate the beauty of plants in our gardens, church altars, in a pretty vase on the table. However, plants are fascinating warriors and chemical factories. Many of our medications are plant based. Have you ever thought about how you would defend yourself if you couldn’t get up and move. What if you were anchored by roots and unable to just leave? Plants have developed many defenses against predators and pathogens. out.
Common milkweed (pictured) is thriving in our wildlife garden because the deer don’t bother it because it contains cardiac glycosides. However, certain insects such as the monarch butterfly use it unharmed and these toxins are used to fend off butterfly predators. Foxglove is left alone because of digitalis.
A plant defense that fascinates me is allelopathy. Allelopathy is a biological phenomenon where one plant inhibits the growth of another through the release of allelochemicals, that greatly affect the growth of other plants either in a good or bad way by leaching, decomposition, etc. In essence, plant allelopathy is used as a means of survival in nature, reducing competition from plants nearby. An example is the walnut tree that releases jugalone so that many plants will not grow under or around walnut trees.
For other plant defenses – this link offers a nice summary without getting too technical – https://www.britannica.com/list/9-plant-defense-mechanisms orhttp://blogs.cornell.edu/…/Plant-Defenses-Guide_Taylor-o4wx… I am obsessing about this today because I am sitting here with a raging left arm, face, and neck rash due to poison oak – and yes I know the plant but it was hiding.