The U.S. Botanic Garden is a living plant museum with exhibits that interpret the role of plants in supporting Earth's diverse and fragile ecosystem and in enriching human life. Its collections date to the 1840s when 250 plants and an unknown quantity of propagation material gathered by the Wilkes Exploring Expedition (1838-1842) were brought back to Washington, D.C. The Garden's present conservatory is a two-part building. The front is a one-story limestone structure with 11 lofty arches inspired by the 17-century orangery at Versailles near Paris. At the rear is a glass and aluminum greenhouse conceived in the glass house tradition first seen in the 1850s Crystal Palace in London. The conservatory was designed by the Chicago firm of Bennett, Parsons & Frost and completed in 1933.

The Conservatory houses a number of permanent exhibits including:

• World Deserts: Filled with succulents, grasses, shrubs and other flowering plants.
• Hawaii: A collection of plants native to Hawaii, where species have adapted to live in the specialized conditions of the remote volcanic islands.
• Children’s Garden: An area where children can play in a garden and learn informally about plants.
• Garden Primeval: A reconstructed Jurassic landscape of ferns and other ancient plant groups that have survived for 150 million years.
• Plant Adaptations: Shows some of the fascinating adaptations that have evolved in the plant world.
• Garden Court: Features economic and ethno-botanical plants — those used in -products that provide our fibers, food, beverages, cosmetics, wood, spices and others, as well as beauty created with colorful foliage and flowers.
• Jungle: A tropical rainforest overtakes an abandoned plantation. The dome rises to 93 feet and has a mezzanine level from which to view the jungle canopy.
• Medicinal Plants: Explores the origin of plant medicine and displays a collection of medicinal plants from all over the world.
• Orchids: An ever blooming, ever-changing display of these mythic plants. The USBG orchid collection numbers about 5,000 specimens, but about 200 orchids are on display at any given time.
• Plant Exploration: Highlights plant discoveries in the wild and in the laboratory. Features changing and seasonal exhibits.
• Southern Exposure: A micro-climate garden featuring North American plants native to the Southeast, the Southwest, and Mexico.
• Rare and Endangered Species: A changing display of rare, threatened, or endangered plants.
• West Gallery: “Plants in Culture” demonstrates how plants provide livelihood, meaning, therapy, ornamentation, tools, symbols, and other enrichments to our everyday lives.