Out of Thin Air

Part of the Water: H2O = Life exhibition.

© Digital Vision/AGE Fotostock

Most plants draw water and nutrients up out of the soil through their roots. So how does a plant attached to the side of a tree, such as a butterfly orchid, get water when its tangle of roots is so far from the ground? A special kind of root tissue, called velamen, absorbs moisture, and sometimes nutrients, from rain and from water running down the tree trunk. To get through drier periods, many orchid species also have thick, bulblike stems that store excess water.