Zephyranthes insularum, common name rainlily, is a bulbous flowering plant in the family Amaryllidaceae, subfamily Amaryllidoideae, native to Cuba and reportedly naturalized in Florida and in parts of Mexico.
Zephyranthes insularum is a small bulb-forming perennial no more than 30 cm tall. Flowers are trumpet-shaped, white to very pale pink.
Zephyranthes insularum <small>H.H.Hume ex Moldenke</small> (i.e. the species named by Hume) is accepted by the World Checklist of Selected Plant Families as a distinct species. Zephyranthes insularum <small>auct. non Hume</small> (i.e. a name applied by some authors other than in the sense intended by Hume) is a synonym of Zephyranthes puertoricensis.