Virtual Museum of Canada
Jardin botanique de Montréal 
Centre for Forest Research

Thirsty hairs

Make a fist and run a finger from the knuckle on your thumb across to the one on your little finger. It's not very far, is it? Now, spread your fingers and do the same thing, this time tracing up and down the outside of each finger. It's much farther, isn't it? Think of your fist as a rootlet and your fingers, the root hairs (Unicellular hair by which the roots increase their surface for absorption.) on it.

Although they represent only a fraction of the rootlets’ mass, the root hairs greatly increase the roots' contact area with the soil, playing an important role in the absorption of water and nutrients. This strategy of having a greater contact area can be seen elsewhere in nature – in your intestines, for instance.

Optical microscopy photo of a rootlet and root hairs of a red pine (Pinus resinosa)
Pinus resinosa
© 1. National Research Council Of Canada, NRC Research Press (Visual Aid only) / 2. Julie Marleau