Wet Roots

Plants that live in wet soil must adapt to the lack of oxygen. Reeds and some sedges, such as those found in freshwater wetlands, have hollow structures that enable the little oxygen they obtain to travel quickly through the plant. Mangrove trees, found in saltwater (marine) wetlands, have a tangle of roots that are exposed periodically to the atmosphere as the tides ebb and flow. Cypress trees, which grow in freshwater swamps, have knobs or "knees" of root material that emerge from the water; scientists speculate that these knees absorb oxygen. The roots of floating plants, such as duckweed or lilies, dangle into water and absorb oxygen.

Wetlands plants also must be efficient at absorbing other nutrients such as nitrogen and phosphorus. For example, in wetlands, nitrogen is most often available as ammonia, thus many wetlands plants have become super-efficient absorbers of ammonia.

Mangrove trees have specially adapted roots for living in wet environments. Photo: © Carolyn Duckworth 2004	Water lilies float on a pond, but their roots extend down to the mud below. Photo: © Carolyn Duckworth 2004
This small wetland plant can thrive even with wet roots. Photo: © Carolyn Duckworth 2004

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