By Megan Jorgensen
Iowa State University
The Screw pine, Pandanus utilis, is noteworthy for its dramatic architecture, numerous uses and aerial prop roots, yet it is not a true pine. Rather, the screw pine is a monocot and instead is a close relative of grasses, orchids and palms. The common name for this plant originated from the strap-like spiny leaves spirally arranged around its branches.
The screw pine is a tropical plant that grows in rain forests and semi-evergreen forests of Madagascar, southern Asia and the islands of the southwestern Pacific. It has a pyramidal shape supported by large stilt-like prop roots that emerge several feet above the ground. In Borneo, New Guinea and other pacific islands, it is often called the walking palm because of the way that the roots gradually carry the plant from one spot to another.
Screw pines are dioecious, meaning male and female flowers are born on separate plants.
Though male plants produce tiny fragrant flowers, gardeners often prefer the female plant for its showy pineapple-like fruit. Although the fruit is edible, it is nicknamed the “famine fruit” because of its unpleasant taste. While the fruit is not useful to humans, the tough leaves not only provide thatching materials for mats and baskets, but also have medicinal properties. The leaves possess anti-diabetic properties, are used to treat skin diseases and serve as a diuretic.
The screw pine is capable of reaching a mature height of 60’ tall but is typically 25’ tall and 15’ wide in the United States. It has a slow to moderate growth rate, and requires full sun to partial shade and well-drained soil. The plant is hardy to USDA Hardiness Zones 10 and 11, but in colder zones serves as a houseplant or conservatory planting.
View the characteristics of this unique plant and more in the Conservatory at Iowa State University’s Reiman Gardens.