As growers and humans we have always had an interest in nature’s extremes, and there is certainly no shortage of these extremes in the plant world. There is perhaps no better example in nature than carnivorous plants. Plants such as the Venus Fly Traps, Pitcher Plants and Sundews have evolved unique ways of supplementing poor soil nutrition by becoming predators. These plants feed off other living things using unique and deadly adaptations.
Venus Fly Traps (Dionaea muscipula)
These small herbs are possibly the most well known of the Carnivorous plants. They consist of a small base of leaves with shoots consisting of a hinged, toothed trap with small pink pads that open like a clam shell. A trigger on the pad acts as a sensor and when activated, shuts rapidly on the intended victim. A native to the eastern coast of the United States, these plants are adapted for harsh marshland soils and lots of sun. They’re normal “diet” consists of ants, small beetles, and of course, flies.
These plants can be notoriously hard to grow and require a daily flushing of distilled water, light or sun cues, and plenty of patience. A good base is recommended like sphagnum moss or sometimes a sandy medium. The plants are used to a summer/winter cue, so timing with sunlight or artificial light is key. These plants need lots of water, and distilled water has shown great results. Traps can take years to present themselves in a mature plant, so patience is key.
Pitcher Plants (Sarracenia purpurga)
A non-motile plant, pitcher plants rely on bait to trap their victims. Modified leaved form a pitcher like trap where digestive juices are produced. The sides of the pitcher are slick and some species have teeth lining their rims to prevent any escape. An irritable odor attracts creatures to its pitcher and they slip down into the pool. With no option for escape, the animal is slowly digested in the pool of juices and the plant is fed.
While some species have an “umbrella” to keep rain from the tropics out of the pitcher, some plants’ pools just become gradually more dilute. These diluted pools still serve a purpose, as they become ideal breeding grounds for many species of insects. Nutrients are also added to the pitcher by tree shrews who have found a convenient use for the pitchers as their preferred bathroom.
Growing them is easier than the Venus traps. Pitcher plants require a sandy, nutrient poor soil, and peat moss is a good medium to grow them in. These plants need full sun, and must not be overwatered. Keeping the tops dry and in full sun will produce the best pitchers in most species.
Sundews (Drosera capensis)
Sundews are small, sturdy plants that offer unique adaptation to their shoots. Small “tentacles” stick off of the shoot, capped with a sticky deposit that ensnares unlucky victims. When an insect makes contact, it is trapped in the sticky mess, as the arms begin to curl up and trap the insect even further. Digestive juices immediately begin to work, slowly breaking down the animal and providing nutrients to the plant. These plants are found in numerous families, and can be found on nearly every continent, quickly becoming one of the most popularly cultivated plants.
Sundews grow well in almost every medium, although a 1:1 sand/peat or LFS/perlite ratio works best. The plants prefer to stay moist and around 50% humidity. Feeding them 2 times per week will help ensure a good growth pattern for these plants. The plant itself is fairly tolerant of a wide-variety of environments, so they are a good choice for a low-maintenance carnivorous plant.
If you are interested in seeing any of these exotic plants, San Diego State University has a small public display in the Life Sciences North building on the first floor. San Diego
Hydroponics and Organics has kindly donated the lighting system for this display, and the plants have been thriving there for years. These plants are under the expert care of Bob Mangen, the greenhouse master at SDSU. Bob has kept this display for over 10 years, and had pioneered new techniques in caring for these unique plants. Greenhouse visiting hours are Monday-Friday, 9am-11am.