They're called volatile organic compounds or VOCs, that emanate from adhesives, solvents, furnishings and even clothing in well insulated energy-efficient homes. Chemicals used in manufacturing emit fumes that have so affected indoor air quality that the World Health Organization conducted a study to determine how to mitigate the problem. The study included a test of various house plants in the home and whether long term presence affected air quality indoors. Their hope was to find an affordable, widely adaptable method to improve indoor health in rich and poor alike.

The study proved that a certain wandering Jew (name no longer official), now renamed Purple Queen was the best at taking up pollution. Botanically named Tradescantia pallida, also listed under genus Setcracea is named for its pale flower color. This is the purple groundcover you see around the more sheltered parts of the Coachella Valley, often in mass plantings, or frequently used in pots and hanging containers where the amazing burgundy foliage is enchanting up close.

Another study in the Amazon rain forest used this same plant to help remove pollutants, namely heavy metals from contaminated soils. Here too this unique Mexican house plant proved it could absorb toxins through its roots too. Thus it became the poster child for phytoremediation, the natural ability of some plants to bioaccumulate, degrade or render harmless contaminants in soils, water or air. This odd scrambling semi-succulent perennial was transitioned from an ordinary house plant into a world class hyper accumulator with great potential to solve some of our most vexing pollution problems.

I first saw purple queen thriving at Clark Moorten's garden behind the walls in the private collections. It had found a home between flats of sun tender Haworthia truncata that receive weekly irrigation. When spring arrived I fell in love with dime sized flowers that stand out in striking contrast amidst the dark burgundy foliage.

I was hooked on this gorgeous beauty that thrived on little water and neglect, so I brought cuttings home. I planted them on the north side of the house where the evaporative cooler water drains into the ground. Tradescantia thrived there, turning into a dense, rich clump proving its natural adaptation to this problem exposure. Yet this plant surprises me because I've seen it just as happy in open ground. My conclusion is that water availability, not sun, is the reason it prefers one place or another.

If you think about its origins along the eastern edge of Mexico you realize this the origin of our dreaded summer monsoons. Plants that are well adapted to extreme storms and humidity during very hot summers withstands our own monsoon season with flying colors.

Purple Queen is among the new world genus of spiderworts, but it likely arrived here in the desert as a house plant left outdoors at the end of the season by snowbirds. That's what happened in Florida where this vigorous plant found a new home, naturalizing far and wide. Today Purple queen is so happy she's become an invasive planta non grata in Florida and is an official member of the do-not-plant list. This is also true in rainier parts of Australia where it's now banned as a dangerous exotic. Fortunately here in the desert we are too dry for unirrigated plants to survive.

Tradescantia is an excellent choice for beds along the north side of perimeter walls where few plants grow down low where light is minimized. Try using it to add color to nooks in the architecture, atrium or patio. There are few other plants in the desert that appreciate conditions under tree canopies as well. Above all, though, be sure there is suitable irrigation or the plants grow spindly and brittle. Sometimes occasional heading back of the most vigorous growth tips, like nipping back a houseplant, makes purple queen more dense over all.

Root your cuttings and then tuck them into mixed color pots and succulent compositions since they share the same water demands. This is a perfect choice for blending with white foliage such as ghost Euphorbia, the silvery fuzzy kalanchoe and large mammilaria cactus for a fresh new look. Another option is to let it dangle off shelves on the patio or wall mounted containers on that shady wall. There is no better accent for around your fountain.

Sometimes amazing plants live among us but we fail to really grasp their potential in our outdoor living areas because we've profiled them as houseplants. Tradescantia pallida deserves a new look, not only for drought but its value in phytoremediation. Above all, this plant demonstrates what makes our valley's tropical desert counter intuitive to gardeners, because house plants go outdoors for the winter and succulents come inside for the summer.