The Garfield Park Conservatory in Chicago: It's just a glass house full of plants. They are organized by plant families or by habitat type or by function. They are but a sampling of the plants growing in places far around the world. They are but a tiny slice, the few that are adapted to greenhouse life and small and polite enough to fit the confines of the structure and predictable enough to be green year around: Deciduous plants need not apply here. Yet on a day when the temperatures stay in the single digits and we are just grateful the numbers are not preceded by a minus sign, it is a warm and welcome change to retreat to the house of strange and varied plants under glass.