Plants bring color, usually green, into a room. They bring companionship, as anyone can attest who has ever asked a begonia if she'd like another drink of water. And some bring cleaner air as well.

Chrysanthemums, for instance, have been found by National Aeronautics and Space Administration scientists to be "superior" at removing benzene from indoor air. Philodendrons are pretty good at it too, and easier to grow indoors. The spider plant, another easy grower, takes in carbon monoxide. Several others can reduce formaldehyde and nitrous oxide.NASA plans to keep on studying house plants, and the Associated Landscape Contractors of America is planning to study with them. And if health plants aren't as fashionable in the '90s as health foods were in the '70s, we'll eat our ficus.