Venus Flytraps
DB: This is Earth and Sky. Imagine stumbling on a bog filled with carnivorous plants. There are pitcher plants, sundews and butterworts – and one plant that stands out as a global rarity – the Venus flytrap.
JB: This plant’s technique for capturing insects would be horrifying if the plant were as big as a man – instead of only a few centimeters tall. When a fly lands inside a gaping, jaw-like leaf, it touches trigger hairs. The cells along the leaf’s hinge swell rapidly with water – and force the leaf to snap shut. The Venus flytrap digests the fly and ingests nitrogen that’s lacking in poor soils.
DB: These plants thrive in tough living conditions – sandy, acidic soils that are wet most of the year – in long-leaf pine forests. Frequent fires in these forests act like a dose of fertilizer for these meat-eating plants. But Venus flytraps have always had a small geographic range, the coastal plains of North and South Carolina. Today, less than 10 percent of their habitat remains.
JB: The key to survival for Venus flytraps in the wild lies in preserving our last stands of long-leaf pine forests – and in protecting wetlands and prescribing fire. Finally, experts say it’s important not to buy any Venus flytrap plant unless you can be sure it didn’t come from the wild. Special thanks today to the National Fish and Wildlife Foundation, and to the U.S. Forest Service. We’re Block and Byrd for Earth and Sky.
Our thanks to:
Wayne Owen, Regional Plant Ecologist
USDA Forest Service/Biological & Physical Resources
Atlanta, GA
Alan Weakley
Chief Ecologist
Association for Biodiversity Information
(Nonprofit organization that gathers and provides information for land managers. )
Earth & Sky’s interview with Alan Weakley:
August 20, 2001
Where found:
The Venus flytrap is endemic to the coastal plain of North and South Carolina, primarily North Carolina ? almost all the plants in the wild are found within a 100-mile radius around Wilmington. This particular part of North Carolina has veryacidic, nutrient poor, coarse soils.
It is naturally rare and in addition to that has suffered from human-caused problems. It is a monotypic genus?meaning there is only one species in the genus. Sometimes Venus flytrap is treated as a monotypic family, or in the sundew family ( insectivorous plants that rely on the flypaper style rather than the active trap).
Why it was restricted to that area has been lost in the mists of time. There may be ties to water levels, glaciation, and climate change. Very distinctive species like this one that are monotypic can’t evolve quickly. It has probably been around for a long time. It’s fair to say that in the midst of climate change, this area has become the refuge for this plant, but it may once have been more widespread. It is able to grow in Florida and a few other places where people have planted some Venus flytraps. (note: not a condoned practice by agencies?see background info).
Insectivory in plants:
Insectivory in plants is scattered evolutionarily among different groups of plants and has evolved multiple times. It is also scattered geographicially. Southeast Asia and Australia may have the greatest number of insectivorous plants. But the southeast coastal plain of the US is a global hot spot for insectivorous plants.
The general explanation for carnivory in plants may not be provable. But the general belief is that it’s related to habitats with nutrient deficiencies, such as nitrogen. The belief is that the plants with insectivory are capturing additional resources that allow them to compete in an environment that is nutrient deficient. Venus flytraps and other insectivorous plants occur in very acid soils. Venus flytraps occur in acid sands that remain saturated for much of the year.
Plant mechanism..
The trigger hairs create a chemical change in cells so the cells fill with water rapidly and are located along the hinge. The expansion physically causes the trap to close. It works like an open door, when you wedge something in the backside of the hinge to slam the door shut.
Conservation:
The Venus flytrap has always had a restricted distribution, although it used to be commonly found in that region. As the long leaf pine ecosystem was converted to agricultural lands and fires were suppressed, the open pine savanna became restricted to less than 10 percent of its original extent. As much as 90 percent of the habitat is gone.
This plant gets more press because it is also actively exploited. That is significant, but overshadowed by habitat loss. We’ve reduced the habitat to a fraction and now on that fraction we have that problem of direct exploitation. It’s a double whammy or one-two punch.
Holly Shelter Game Lands may contain the largest population?at least 50 percent of what’s left in the wild is there. There has been some serious effort made to lessen the poaching problem. Still, the most serious issue is habitat protection and management for fire.
Without fire, the forests fill in and out-compete and shade out the smaller plants. The habitat requires the frequent disturbance to maintain the savanna. Fire is the great leveler that keeps the bullies out. If you burn a Venus flytrap population, they respond with five times the vigor.
An interesting side note?There is a Venus flytrap moth and the caterpillar depends exclusively on the Venus flytrap for food. That makes it even rarer than the flytrap.
Conservation status
It is not on the federal list, but it is protected on the state endangered species list. It is also listed on CITES, the international regulatory organization, to restrict its import and export. There has been a tremendous fascination in Europe and is cultivated in large numbers in Holland and Germany.
Legally cultivated?
They can be legally cultivated and much is done by tissue culture, which is like cloning. Therefore that has no further impact on the natural populations. That may help meet the supply without wild collection. Reputable sellers should be able to label plants as cultivated.
