Friday 11 January 2013

How a Marsh Pitcher Plant catches its diner.

Marsh, or Sun, Pitcher Plants (Sarraceniaceae) are Carnivorous Plants growing in nutrient poor marshy conditions in South America. They have the tubular leaves of all Pitcher Plants, but lack the lids of many such plants (Pitcher Plants are not a true taxonomic group, but the result of convergent evolution; the different groups of Pitcher Plants are not closely related), nor do they produce their own digestive enzymes, being reliant instead on symbiotic Bacteria to digest their prey.

In a paper published in the Proceedings of the Royal Society: Series B, Biological Sciences on 19 December 2012, Ulrike Bauer or the Department of Plant Sciences at the University of Cambridge, Mathias Scharmann of the Department of Animal Ecology and Tropical Biology at the University of WürzburgJeremy Skepper of the Department of Physiology, Development and Neuroscience at the University of Cambridge and Walter Federle of the Department of Zoology at the University of Cambridge, examine the way in which the Marsh Pitcher Plant, Heliamphora nutans, captures its prey.

Marsh Pitcher Plant, Heliamphora nutans, growing at Kew Gardens. Wikipedia.

Heliamphora nutans secretes nectar from the inner surface of an appendage on the upper part of the leaf known as a nectar spoon. Beneath this the inner surface of the upper part of the leaf, called the pubescent zone, is covered with a dense carpet of inward-pointing hairs, thought to be associated with prey capture. Beneath this is a smooth area known as the glandular zone, which contains the water in which the plant digests its prey; this does have some hairs at the bottom, though they are different from those on the upper wall.

The anatomy of Heliamphora nutans. Bauer et al. (2012).

Bauer et al. allowed Ants to access the plants under controlled conditions at Kew Gardens. They found that while the leaves were dry the Ants were able to move over the surface unhindered, but once they were exposed to moisture the hairs on the inner surface of the leaves trapped a layer of water, which caused ants to aquaplane into the trap.

Video showing the fate of Ants on wet and dry leaves of Heliamphora nutans. Bauer et al. (2012), supplementary material.

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