National Tropical Botanical Garden, Botanical garden complex in Kauai County, United States.

The National Tropical Botanical Garden is a garden complex on Kauai that combines two distinct areas: McBryde Gardens with native Hawaiian plants and Allerton Gardens with fountains and water features. Together the site spans 352 acres with diverse landscapes and plant collections.

Congress chartered this institution in 1964 to establish a network of gardens dedicated to protecting tropical plant species. This founding created an organization committed to scientific research and long-term plant preservation.

The Breadfruit Institute, created by the NTBG in 2002, documents traditional uses and cultural practices involving breadfruit and keeps the largest collection of breadfruit cultivars in existence. Its ethnobotanical work records how Pacific islanders grew, cooked and propagated the tree.

Visitors reach the gardens through a center near Spouting Horn Beach Park and can join guided tours lasting about two to three hours. Reservations are required, and the tours show both sections and their plant life.

The NTBG rediscovered Hibiscadelphus woodii in 2019, a plant species previously deemed extinct. The genus name honours Queen Liliʻuokalani, and the find came from a population in a Kauaʻi cliff habitat. The Breadfruit Institute, created in 2002, holds the largest collection of breadfruit cultivars in existence.