The pink hibiscus of heated tropical fantasies, a spiky Louisiana iris with yellow burning at the core of its alabaster flower, luscious bougainvillea, sexy bromeliads. Okay, the profusion of greenery for sale at this sprawling complex, which fills the block between 81st and 82nd streets, isn't much different from that of other run-of-the-mill South Florida nurseries. Log Cabin is unique less for its considerable selection than for its community function. Even serial plant killers can feel good about spending money here on yet another bid at nurturing. Open daily until 5:00 p.m. (10:00 a.m. until 4:00 p.m. Sundays), this nonprofit organization was founded in 1983 to help the developmentally disabled become independent and employable. More than 40 adults attend the program, arriving at 9:00 a.m. to water, fertilize, weed, and help customers. In the afternoon participants study conundrums such as counting change, cleaning, and cooking. Log Cabin graduates also get a hand finding employment. Approximately fifteen alumni currently are working for the Miami Beach parks department and at the nursery, as well as at service-industry jobs in places like McDonald's and Publix. And come December, if you're in the market for a Christmas tree, Log Cabin sells those, too.