What is a Carnivorous Plant?

Surprisingly few definitions of plant carnivory have been published. A simple one can be formulated in modification of Givnish et al. (1984).

To be carnivorous a plant must fulfil two requirements:

  1. it must be able to absorb nutrients from dead animals juxtaposed to its surfaces, and thereby obtain some increment to fitness in terms of increased growth, chance of survival, pollen production, or seed set.
  2. it must have some unequivocal adaptation or resource allocation whose primary result is the active attraction, capture and digestion of prey.

Usually the reason for such exotic behavior is that the plants are adapted to living in very nutrient-poor environments such as acidic bogs and limestone cliff faces. It is estimated that there are over 600 species of carnivorous plants. Many of these are very beautiful and are usually fairly easy to cultivate in the home or garden environment when given proper cultural conditions.

In practice the dividing line between carnivorous and non-carnivorous plants is not so distinct. According to Jan Schlauer:

There is no dividing line because there is no conditio sine qua non for carnivory in plants. It is a syndrome rather than a point mutation, and it certainly has evolved (and *is* evolving, of course) at different times from very different lines.

Thus, at the present time, the following genera are treated as being carnivorous here: Aldrovanda, Byblis, Cephalotus, Darlingtonia, Dionaea, Drosera, Drosophyllum, Genlisea, Heliamphora, Nepenthes, Pinguicula, Sarracenia, Triphyophyllum and Utricularia.

Several members of the Bromeliaceous genera (Brocchinia and Catopsis), along with the "devil's claw family" ( Craniolaria, Ibicella, Martynia, and Proboscidea ) and others are considered carnivores (or possible carnivores) by some authors but are not listed completely in this database as there is no evidence of the production of digestive enzymes. Although Roridula also lacks digestive enzymes, it is included in this database for historical reasons.

Rick Walker
rick_walker "AT" omnisterra.com