Our state is home to many carnivorous plants
like reading good science fiction — not stuff about teenage alien love affairs, but good stuff. My favorite science fiction book is a trilogy called “The Giants Novels” by James P. Hogan. You can probably find them at the public library.
I mention science fiction because it can seem strange and unrealistic. However, as the old saying goes, truth is stranger than fiction. An example of strange natural adaptations are carnivorous plants (more specifically insectivorous plants). North Carolina actually has more native carnivorous plant species than any other place on earth. Many of the carnivorous plants are in the eastern part of the state, but there are some in the Piedmont and mountains.
Carnivorous plants use several strategies to consume insects. There are pitfall traps. This is used by pitcher plants. Their leaves are folded inward to form a slippery vessel filled with a pool of digestive enzymes.
Sundews and butterworts are like flypaper or adhesive traps. These plants’ leaves are covered in glands that exude sticky mucilage.
I think the most popular carnivorous plant is the Venus flytrap. It is like a snap trap. The Venus flytrap leaves are hinged and snap shut when trigger hairs are touched.
Bladderworts are aquatic carnivorous plants that use suction to trap their prey. They have an attractive flower on top of the water, and a trap below the water. The bladder, or sac, is flat. When an insect investigates the flower, it triggers hairs, causing the sides of the sac to expand quickly. This quick expansion sucks water and the insect into the bladder where the insect is digested.
Some plants employ a corkscrew type trap where the channel is lined with hairs that keep the insects from backing out. Ultimately, the trapped insect finds its way down into the plant’s digestive juices and the plant can then absorb the minerals from the insect.
However, insect-eating plants are certainly not the only weird actors in the plant world. Some plants cause beneficial or harmful effects to other plants. These effects are from the release of plant compounds through leaching or root exudation.
The scientific term for this type of plant-to-plant interaction is allelopathy. These plant compounds use many of the same pathways that synthetic (commercial) herbicides exploit. Also, like synthetic herbicides, the allelopathic compounds can alter cell division, pollen germination, nutrient uptake, photosynthesis or specific enzyme functions of the target plant.
The classic example of an allelopathic plant is the black walnut tree. The black walnut produces a compound called juglone, which inhibits the growth of many garden plants. Tomatoes are the most sensitive garden plant. Mature tomato plants wilt if exposed to trace amounts of juglone. This is why black walnut mulch or timbers should not be used in the garden.
Allelopathic interactions also occur when planting cauliflower, cabbage, cress, bok choy or any plants in the Brassicaceae family following a broccoli crop. Broccoli produces a compound that stays in the soil. It reduces the vigor of any plants in its own family that are grown the season following broccoli.
I’ve shared a few examples of strange stuff in the plant world. I have always found science fiction and science fact a lifelong fascination. To learn more about allelopathy, visit http://www.extension.org/pages/18524/how-cover-crops-suppress-weeds
Seth Nagy is the County Extension Director in Caldwell County.
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