Phytoremediation is the science of using plants to help clean up pollution. After all, plants are experts at selectively extracting nutrients and minerals from the soil through their roots. So why can't they be used to remove toxins, too?

Phytoremediation is the science of using plants to help clean up pollution. After all, plants are experts at selectively extracting nutrients and minerals from the soil through their roots. So why can't they be used to remove toxins, too?


Scientists have tested many species for their ability to reduce toxicity in soils, air and water. Among the most important phytoremediation plants are ferns.


Ferns are relatively primitive, dominating Earth long before seed-bearing plants and flowers appeared. In fact, at one time great forests of monster ferns covered much of the globe, but climate change forced them to evolve into smaller sizes. They reproduce by a microscopic spore generated on the back of the leaves. Each genus of fern arranges spores in a different pattern, which is one way of distinguishing the all-too-similar species.


These plants have survived for hundreds of millions of years relatively unchanged. This requires a powerful ability to withstand cataclysmic climate change and survive. The toxins of volcanic eruptions and the cold of ice ages did not make them extinct, like so many other plants we know today only by the fossil record.


One of the most important phytoremediation ferns is the Chinese break fern, or Pteris vittata. Such plants are deemed hyper-accumulators. These are rare plants with a much greater ability to take up heavy metals and other toxins from soil. This break fern is highly successful at extracting a specific toxin, arsenic.


We are just waking up to the potential for arsenic toxicity in the backyard. Because this toxic substance kills insects, bacteria and fungi, it has long been used as a wood preservative. Where arsenic-treated wood has existed in the yards of older homes in the form of fence posts or deck foundations, the decomposing wood can leave a concentration of arsenic behind after the structure has vanished.


Arsenic may be present in the soil if your subdivision is located on the former industrial site of a metal manufacturer. Homes built on land that was formerly an orchard may also find traces of arsenic once used as a pesticide. During the 19th century, arsenic was a common pesticide and it may be present on the grounds of homes from that era.


In the past, we saw ferns as beautiful green foliage plants. Today they are becoming hardworking pollution fighters.


This new science of phytoremediation looks at how nature tailored certain plants to clean her earthy carpets, and now they'll do the same for yours.


Maureen Gilmer is an author, horticulturist and landscape designer. Learn more at www.MoPlants.com. Contact her at mogilmer@yahoo.com or P.O. Box 891, Morongo Valley, CA 92256.