Separate areas for roses, herbs and native plants are found within these 33-acre gardens. The centerpiece is the Lucile Halsell Conservatory, a 90,000sq-ft cluster of individual glass houses tucked into the earth around a courtyard sunk 16ft underground to escape the hot Texas summers. Beneath the conical and triangular roofs, conceived by architect Emilio Ambasz, are special collections of tropical, desert, alpine and aquatic plants.