Carnivorous Plants

General rules

  • plants are producers

  • Animals are consumers

  • Plants are comparatively immobile

  • Animals are on the offensive and search for plants to eat

  • This leads to an ‘evolutionary arms race’

  • at least 800 species of plants predate animals

  • Carl Linneaus - carnivorous plants go “against the order of nature as willed by god”

  • Darwin liked carnivorous plants

  • they are not a single linniage of common decent

  • they are ecologically defined

  • they must be adapted to: “attract, trap or digest prey, be capable of absorbing nutrients from killed animals and obtain some benefit in terms of growth, survival or reproduction”.

  • all are angiosperms

  • most are terrestrial

  • divided into five types: flypaper, snaptrap, pitfall, lobster pot and bladder suction

  • origins estimated 72 to 8 million years ago

  • evolves well after angiosperm radiation

  • fossil record is limited

  • earliest fossil 35—47 million years ago, tentacle fragment

they are usually restricted to:

  • low soil quality

  • high water availability

  • high light intensity

  • generally peatlands or bogs

  • peatbogs contain twice as much carbon as the worlds forests

Benefits of being carnivorous

  • supplementing low root nutrient intake

  • growth

  • earlier flowering

  • increased seen set

  • increased rate of photosynthesis

  • increased root activity

  • increased seedling growth

costs

  • two fold form trap formation leading to increased resource requirement

  • Mucilage

  • Volatile organic compounds - used to attract plants, can smell of fruit, floral or decay. May also produce nectar as a lure. colour can also be used.

  • enzymes

  • assimilation

Snap traps

  • require rapid movement. venus flytraps and Aldrovanda.

  • Venus flytraps are triggered be trichomes on each lobe.

  • connected ion channels generate and electrical signal.

  • Trap closes when the electrical charge reaches threshold

  • Aldrovanda is faster than the flytrap

Mucilage (flypaper)

  • Polysaccharide - Drosera, pinguicula, etc.

  • Resin - Roridula

  • use capillary thinning (low surface tension), sheer thinning (viscosity decreases under force), viscoelasticity, high viscosity

  • Digestion - the leaf surface can: roll and tentacles bend for increased prey contact, leaf rolls or is rolled to contain digestion fluid, leaf doesn’t move

Pitcher plants

  • three independent linages

  • Sarraceniaceae (family), Nepenthes (genus), Cephalotus (genus)

  • use slippery liquid infused porous surfaces, inwards facing hairs, and waxes

  • Contact to wax results in wax attaching to legs leading to further slipping in upper and sometimes lower layers

  • sticky fluid in the pitcher help retain prey

  • fluid has low surface tension, fluid forms long lasting filaments, flid strongly resists dewetting

  • Digestion happens as sealed traps or pit/stomach

  • Can use water based pool or commensal organisms