Nature on our doorsteps: The ghost-like Toothwort

Rosaleen Dwyer is the County Heritage Officer at South Dublin County Council – every week she gives us an insight into the natural heritage around us and the beautiful biodiversity of the plants and creatures.

There are some remnants of old riverside woodland along the River Liffey which can offer glimpses of some of the rare and uncommon plants that can occur in these disappearing habitats.

One of these plants is the unusual-looking Toothwort. Toothwort does not contain any chlorophyll, which is the pigment that gives plants their green colour.

Plants also use chlorophyll to make their own food, using sunlight, oxygen and water.

Without chlorophyl, Toothwort’s flowering stems appear as a white spike which is often tinted with pink. The plant has pale, fleshy, scale-like leaves, and its individual flowers occur clustered along one side of the stem, which tends to arch to one side.

For most of the year, Toothwort exists as a hidden underground stem, or rhizome.

Toothwort’s arching stems support unusual-looking pale flowers and scale-like leaves

In March and April, it sends up its ghostly-looking flowering shoots, pushing their way up through the layers of decaying leaves on the woodland floor.

Because it has no green chlorophyll with which to make its food, Toothwort has had to adapt by becoming a plant parasite.

It attaches itself to the underground roots of woodland trees and shrubs. It then taps into the tree’s internal circulation system which moves water and nutrients around the tree.

By connecting into this system, Toothwort can draw all the food it needs for its own growth.

Toothwort also has another interesting adaptation. The leaves of normally green plants are covered in tiny pores which allow excess water in the plant to evaporate off into the air.

Toothwort’s scale-like leaves do not have leaf pores, so it has evolved another way of removing excess water.

Its pale leaves overlap one another along its stem and rhizome, forming little cavities along the stem. When Toothwort has taken all the nutrients it needs from the tree’s watery sap, it exudes the waste water into these tiny spaces under its leaves.

This waste can then slowly leak away into the plant’s environment, making room for Toothwort to draw even more nutrient-rich water from its host.