Science News

Plants hide too!

The animal kingdom is full of species that do their best to hide from predators by adopting all sorts of clever camouflage to help them blend with their surroundings and not get spotted. And now it seems that some plants might do something similar.

Many plants are brightly coloured to attract pollinators or they take on the colour of the chlorophyll pigments they use to generate energy by the process of photosynthesis.

Matthew Klooster from Harvard University in US and colleagues have been studying an unusual plant called *Monotropsis odorata*, which doesn't have any chlorophyll because it gets all the food it needs from mycorrhizal fungus that live in close association with their roots.

Freed from the constraints of photosynthesis, this plant has the option of adopting different colouration to suit its needs.

As Klooster and the team discovered, it seems Monotropsis odorata does its best to hide from plant-munching herbivores by covering vulnerable purple flowers and stems in brown bracts that resemble dead, brown leaf litter.

By analysing the colour of light reflected by these bracts, the researchers found that they closely match the colour of dead leaf litter.

They also found that in the wild, plants with more intact brown bracts suffered around 20% less damage from herbivores compared to plants in which bracts had been experimentally removed. Plants with more intact bracts also produced between 7 and 20% more mature fruit over the two-year study than plants with no bracts, demonstrating the major advantage that this camouflage can have on individual plants.

The odd thing is that these plants don't want to disappear altogether, because they still rely on animals paying them a visit to disperse their pollen and seeds. Klooster and the team saw bumble bees successfully finding the flowers of these plants and think perhaps the bees are lured in by a sweet scent that doesn't attract herbivores - an idea for another study to work on.

So it seems that cunning camouflage is no-longer a unique characteristic of animals, but plants can do it too.

30th Nov 2009