Profile America — Thursday, March 6th. The Philadelphia Flower Show — the largest such indoor event in the world — winds up this weekend. Some 265,000 visitors are expected to have attended by the time the show closes on Sunday. The Philadelphia show started in 1829 and now covers 33 acres. The show now under way features a symbiosis of fine art and gardening, dubbing the event "articulture." In the U.S., close to 70 percent of households take part in some form of gardening. To aid them, across America, there are nearly 16,000 flower, nursery stock, garden center and farm supply retailers, doing nearly $31 billion of business annually. You can find more facts about America from the U.S. Census Bureau, online at <www.census.gov>.