Ipu is a type of squash known as a "bottle gourd" that is cultivated not so much for its food value (although if harvested young, can be eaten) but for the utility of the dried fruit. This plant, also called "calabash" in some places, is a very ancient one in terms of domestication and has been utilized by indigenous peoples all around the world tropics for at least 9,000 years.

The vine grows very fast during the wet season and produces numerous hard-shelled gourds that can be fashioned into bottles, bowls, spoons, and drums. In terms of shape, numerous cultivars exist, the ones with a long neck above a bulbous base especially favored for carrying water.

Use as a musical instrument, called an ipu hula, is uniquely Hawaiian: a drum fashioned from a small round gourd glued inverted to the top of a larger, more elongated gourd (ipu heke). In ancient times, the two parts were glued together with sap from ‘ulu. A single large gourd drum is called an ipu heke ‘ole.