The nose knows and plants don’t have noses, but there are some fun photos of tree trunks that appear to have them. Can plants smell? Not the way animals do, but they do have senses, a lot of them.
Like humans, plants have the sense of smell, taste, hearing, touch, sight, proprioception, and vestibular sensation. Additionally, plants have at least thirteen more senses! We are aware that our beloved cats and dogs are able to sense and hear far more than we are capable of doing, but we don’t seem to attribute this ability to plants. Scientists have found that plants have the ability to sense, but in ways that are unique to them; just as the increased senses of cats and dogs are unique. Please understand, I am not comparing plants to dogs, cats, or humans, rather, I am using comparisons to help us have a better understanding that a living organism isn’t necessarily an “it” because an organism does things differently.
Ever have a stopped up nose? The recent pandemic affected some people by suppressing their ability to taste and smell. Many recovered this ability but some have not. Scents are complex molecules that are released by many beings. Scents are used to determine foods, poisons, environments, and to attract pollinators. The inability to smell is debilitating. Many experiments have been conducted to demonstrate that plants have a sense of smell.
Like humans, a plant’s sense of taste and smell are interconnected. Some of the sense of smell takes place in the plant’s roots. The roots taste for chemicals such as nitrogen, phosphorus, potassium, or water. The roots will grow where it can find the nutrients needed for plant growth, and will up-take these nutrients through the roots. Some of the tasting is done in the leaves and stem. When a caterpillar starts chomping on a plant, it releases chemicals through its saliva. The plant detects these chemicals (think kissing someone who has bad breath). When plants detect these chemicals, they start manufacturing a counter-chemical that will make itself unsatisfying. (You might grimace and back away but a plant can’t do that). The plant produces these chemicals for the leaf the caterpillar is on as well as the surrounding ones, in case the caterpillar only moves one leaf over. If this defense doesn’t work, plants can up the chemical game and make themselves so disgusting to eat that caterpillars have been known to eat others of their own kind. Yes. Plants can make carnivores out of vegetarians. The defense chemical responsible is methyl jasmonate. It makes the plant not only taste bad to the caterpillar but it causes a counter attack in the caterpillar body. The energy to create this defense has a high cost value for plants, so you can imagine the resource output for a plant or group of plants, over time, can be exhaustive. If the infestation is large, the cost of defense may defeat the plant or group. As a side note, wild tobacco uses nicotine to attack anything with muscles to avoid being eaten. This is its chemical defense. Black Walnut and sunflowers have their own defenses to keep potential rivals out of their area.
There is so much more to know and discover! Plants are so amazing!
Note: If you are interested in learning more and would like me to speak with your group, please contact me.