Most of us think of plants as passive forms of life that quietly go about doing plant stuff, like growing, cleaning the air, and producing flowers and fruit. But have you ever thought a plant could catch and eat another organisms?
We use plants for many different things including food, aesthetics, clothing, fuel, and building materials. Plants have a disadvantage to most other forms of life in that they cannot run away when we cut them down or when an insect decides to make them into lunch. But they do have ways of fighting back through chemicals that can cause itching, bitter taste, or even poison us. Some of the most fascinating plants are ones that have evolved to turn the table on insects and make them into lunch.
Most plants use their root system to draw nutrients from the soil. Leaves absorb carbon dioxide form the air, and through the process of photosynthesis use sunlight to create energy to grow and produce flowers and fruit.
Some plants grow in very poor soils and cannot get adequate nutrients through traditional means, so they have developed leaves that can catch insects and take the nutrients from them that they cannot get from the soil. These are known as carnivorous plants.
The most popular and well known of the carnivorous plants is the venus flytrap (Dionaea muscipula). The venus flytrap has leaves that look like miniature traps. Three little hairs on each inner side of the leaf act as triggers for the deadly trap, when an insect touches two of the hairs within twenty seconds of each other, the trap closes and traps the unsuspecting insect. As the insect moves around in the trap, the leaves produces enzymes which help to digest the insect and allows the plant to gain the required nutrients.
American pitcher plant
Another carnivorous plant that grows natively in America is the American pitcher plant (Serracenia). These plants produce tube-like pitchers that are actually modified leaves which fill with water and digestive enzymes. The plant attracts insects by producing nectar under the top of the leaf which looks somewhat like a lid. There is a smooth lip along the top of the pitcher which causes the insect to lose its footing and fall into the pitcher. The inside of the pitcher is smooth and waxy and there are also downward pointing hairs which all prevent the insect from crawling back out. The insect eventually drowns in the fluid where it is slowly digested by the plant.
Another less known carnivorous plant is the sundews (Drosera). This plant looks and acts similarly to fly paper. The leaves have little hairs with a little bead of nectar on each one. When an insect comes to eat the nectar it finds itself stuck to the hairs, and the leaves slowly curl around the insect. Once the leaf is tightly curled around the insect it produces digestive enzymes which digest the insect.
Another carnivorous plant similar to the sundews is the butterworts (Pinguicula). Pinguicula means “little greasy one” in Latin. This plant produces little purple flowers that look similar to violets, but their leaves are much less friendly. Butterworts have herbaceous leaves which grow in a rosette form and have glands that produce a sticky substance which traps and digests the insects.
Tropical pitcher plants
The tropical pitcher plants (Nepenthes) are the largest of the carnivorous plants, there have even been reports of finding rats in some of the largest pitchers. These plants grow in more humid areas in the jungle. These plants have climbing stems with glossy leaves. The midrib of the leaves extend and a pitcher forms at the tip. The pitchers function similarly to the American pitcher plants by producing nectar to attract insects and when an insect slips into the pitcher they drown in the liquid where they are then digested.
Most people think of carnivorous plants as exotic plants found in the depths of the jungle that can only be grown in a terrarium. Though there are some species, such as the tropical pitcher plants and some species of sundews and butterworts, that are found in warm humid climates and will need to be grown in a greenhouse, there are many that are native to North America.
Grow your own carnivorous plants
Light: North American carnivorous plants require full sun to grow. A good rule to go by is if you have enough sun to grow tomatoes, you have enough sun to grow carnivorous plants.
Water: Because these plants grow in poor soils, it is actually harmful to water them with regular water, and it is recommended to water your plants with distilled water. Also make sure to keep the soil moist at all times. A good method to do this is to place them in a shallow container with about an inch of water.
Winter care: North American carnivorous plants are perennials and actually need a period of cold temperatures, or winter dormancy, to rest so that they can grow back in the spring with vigor. If you are growing your plants in containers they will need some protection if the temperature gets below 20° F for longer than a couple days. The reason to protect your plants is not to prevent freezing, but to prevent them from getting dehydrated. To protect your plants for the winter months, clip off the larger leaves in late fall when the plants have experienced a few light freezes. Place your plants in about an inch of water to keep the soil moist, spray them with a sulfur-based fungicide to prevent mold from accumulating, and then completely cover them with mulch. Make sure to check on your plants periodically for signs of mold and to keep the soil moist.
For more information about carnivorous plants and how to grow them, here are a few recourses I have found helpful.
The Savage Garden, Revised: Cultivating Carnivorous Plants. by Peter D’Amato