Carnivorous Plants Online

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Carnivorous Plants Online
Botanical Society of America

Carnivorous Plants / Insectivorous Plants
The Botanical Society of America is pleased to provide the "Carnivorous Plant" pages. We are in the early stages of developing this section of our site; check back regularly. In the meantime, enjoy the images (mainly donated by members) and the stories they tell. We hope these strange and interesting plants open up your possibilities for asking new questions about the fascinating lives of plants!

Carnivorous plants have the most bizarre adaptations to low-nutrient environments. These plants obtain some nutrients by trapping and digesting various invertebrates, and occasionally even small frogs and mammals. Because insects are one of the most common prey items for most carnivorous plants, they are sometimes called insectivorous plants. It is not surprising that the most common habitat for these plants is in bogs and fens, where nutrient concentrations are low but water and sunshine seasonally abundant. As many as thirteen species of carnivorous plants have been found in a single bog (Folkerts, 1982). Most plants absorb nitrogen from the soil through their roots. But carnivorous plants absorb nitrogen from their animal prey through their leaves specially modified as traps.

Traps work in a variety of ways.
Pitfall traps of pitcher plants are leaves folded into deep, slippery pools filled with digestive enzymes.
Flypaper (or sticky or adhesive traps) of sundews and butterworts are leaves covered in stalked glands that exude sticky mucilage.
Snap traps (or steel traps) of the Venus flytrap and waterwheel plant are hinged leaves that snap shut when trigger hairs are touched.
Suction traps, unique to bladderworts, are highly modified leaves in the shape of a bladder with a hinged door lined with trigger hairs.
Lobster-pot traps of corkscrew plants are twisted tubular channels lined with hairs and glands.

Carnivorous plants are fascinating because, even when they are not trapping insects, their unusual forms are intriguing. However, you should not collect plants in the wild because most of them are relatively rare. Habitat destruction and over collection are two of the greatest conservation threats to carnivorous plants. If you are interested in growing carnivorous plants in your home or classroom, purchase the plants from a reputable grower who uses tissue culture or vegetative means to grow the plant, or starts them from seeds.

Unraveling the story of carnivorous plant evolution and ecology has occupied biologists for centuries. Charles Darwin's extensive experiments confirmed the carnivorous habit for several genera. Carnivory has been documented in at least 9 plant families and 600 species.

We now know that the carnivorous habit evolved independently in many plant lineages (Albert et al., 1992; Ellison and Gotelli, 2001; Cameron et al., 2002; Muller et al., 2004). Pitfall traps evolved independently in four plant groups (the eudicot orders Caryophyllales, Oxalidales, Ericales, and the monocot family Bromeliaceae), and sticky traps, in at least three (the Caryophyllales, Ericales, and Lamiales). These are examples of convergent evolution. In contrast, the snap trap and lobster-pot traps evolved only once among carnivorous plants. In the descriptions below, the plant groups and names follow the Angiosperm Phylogeny Group II (1993) and Peter Stevens' Angiosperm Phylogeny Website, which do not use formal classification ranks above the level of the order.

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