Dr. Lew Feldman, Garden Director
Have you ever wondered about the how and why of “holes” in leaves of plants, like Philodendron?
Whereas we know quite a lot about the mechanism resulting in the holes, we are not sure of the purpose of these holes. Some workers have suggested that because Philodendron is a climbing plant, often found growing at the top of the tree canopy, where winds are strong, that the holes allow gusts of wind to pass through the leaves, thereby reducing possible wind damage. But other suggestions have also been advanced for the functions for these holes. Perhaps one of the most original ideas is that the plant makes holes in its leaves so as to trick potential predatory insects into “believing” that the leaf is damaged. According to this hypothesis, the insect would not “want” to lay its eggs on supposedly damaged leaves. But there are a number of other clever suggestions, including the proposal that the holes function in keeping the leaves cool. Can you think of any additional reasons for these holes?
Regarding the developmental mechanism accounting for hole formation, we know that the holes begin to form very early in the development of the leaf and result from a process known as programmed cell death, in which groups of cells are fated to die during development, leading to the formation of the holes.