Carnivores of the Plant World

​Way, way back at the start of time…….. Ok, maybe not that far back, but way before your parents were born, naturalists found the idea of meat eating plants laughable.  Even the great Carlous Linnaeus (1707-1778) dismissed the idea as ‘against the order of nature’.  A century later, when Charles Darwin’s observations of plants capturing and digesting insects was reported, one botanist rejected the studies as “scientific garbage”.  But today we know the earth is round and some plants are carnivores. 
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So, who are these plants that like to munch down on an insect or two. 
The beasts of the plant world that go against the ‘order of nature’ and were sent to the rubbish tip of science.

There are about 600 species of carnivorous plants, found over 9 different plant families.  They are often called insectivores, as insects are their most common prey, although some don’t mind munching down on a frog or a small bat.  They are usually found in areas with poor soil that have a low nutrient content.  Carnivorous plants absorb most of their nutrients from animal prey, unlike most plants which absorb nutrients, like nitrogen, through the soil.
 
Not all plants that trap or kill animals are considered carnivorous.
To be carnivorous a plant must:

1. Capture and kill prey
2. Digest the prey and
3. Get a significant benefit from nutrients provided by the prey

There are many plants with some features of carnivorous plants, but if they kill an animal and do not derive significant nutrition from the prey, they are considered to be murderous plants.
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There are five different types of traps used by carnivorous plants.  The traps are made from specially modified leaves.  They lure in prey using bright colours, nectar, guide hairs, and/or leaf extensions.  The types of traps are …..

1. Pitfall trap – the leaves are folded into deep, slippery pools filled with digestive enzymes. Found in pitcher plants.
2. Flypaper trap (sticky or adhesive traps) – the leaves are covered in stalked glands that exude sticky mucilage. Used by sundews and butterwort plants.
3. Snap trap (steel trap) – have hinged leaves that snap shut when trigger hairs are touched.  Found in Venus flytraps and waterwheel plants.
4. Suction traps – have leaves in the shape of a bladder, with a hinged door lined with trigger hairs.  Only found in bladderworts.
5. Lobster pot – have twisted tubular channels lined with hairs and gland.  Found in corkscrew plants.

Pitfall trap

Flypaper trap

Snap trap

Suction trap

Lobster pot trap

                                                               Lobster trap photo is from Carnivorous Plant Resource

Four more plant facts for you ....

1.   Most carnivorous plants will grow without eating prey, but they grow much faster and reproduce better
​     with the nutrients they gain from munching down.

​2.  Carnivorous plants never user their flowers as traps.

​​3.  The largest carnivorous plant is Borneo’s Nepenthes rajah,
​     whose pitcher can hold more than 1.5 litres of fluid. 

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Photo: Alexander R. Schmidt, University of Gottingen

​4.   The oldest carnivorous plant leaf fossil is 35-47 million
​      years old.  It was found in amber on the Baltic coastline.

​           What type of trap do you think it used?

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This fantastic photo of the glands of Drosera regia was found on the International Carnivorous Plant Society's web site.  Find a link to their website and other resources below.

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Other Resources

Botanical Society of America
botany.org/Carnivorous_Plants/Utricularia.php

Carnivorous Plant Resource
carnivorousplantresource.com/portfolio_category/genlisea/

Discover Magazine
discovermagazine.com/2015/oct/20-20-things-carnivorous-plants

Encyclopeadia Britannia
www.britannica.com/plant/bladderwort

​International Carnivorous Plant Society
http://www.carnivorousplants.org

Mother Nature Network
www.mnn.com/earth-matters/wilderness-resources/blogs/5-sticky-facts-about-carnivorous-sundew-plants

New Scientist
www.newscientist.com/article/dn26646-first-carnivorous-plant-fossil-is-40-million-years- old/

Sciencing
sciencing.com/pitcher-plant-5385098.html

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