screwpine, any plant of the genus Pandanus, tropical shrubs or trees characterized by aerial prop roots, ranging throughout the Old World tropics, especially in the Pacific. The usually spiral arrangement of clusters of long, slender leaves gives the genus its common name. Locally, screwpines are an important source of thatch, matting, clothing, and edible fruit. Although none are indigenous to the United States, several species (especially P. candelabrum, the candelabrum tree) are cultivated as ornamentals in the South and in greenhouses. The genus is classified in the division Magnoliophyta, class Liliopsida, order Pandanales, family Pandanaceae.