#2: Palm trees.
Palm trees seem particularly good at removing indoor air pollutants, particularly formaldehyde, and fortunately, they're all relatively easy to care for. The best at formaldehyde removal is the Dwarf date palm, which is closest in appearance to the palm trees that remind you of warmer climates (a good cure for the winter blues). But you'll also get clean air with a bamboo palm, areca palm (pictured left), lady palm, or parlor palm. Another plus: Palms like cooler temperatures, in the 60 to 75 degree range, so they force you to be energy efficient and lower your thermostat.