Screw pines are a favorite landscape item in tropical climates and are especially useful in wet soils and adaptable to both fresh and salt water.
Screw pine is a palmlike evergreen with an upright stem (trunk) to 30 ft (9 m) or more high, and many horizontal spreading branches. At the end of each branch is a spiral rosette of long, linear leaves armed with small reddish teeth along the margins. Old leaf scars spiral around the branches and trunk, like a screw. The dark green leaves are around 6 ft (2 m) long, rather stiff, and have a waxy texture. Screw pine produces numerous aerial stilt roots that grow down to the ground and help support the branches which may spread to be wider than the tree's height. Screw pines are dioecious: The male plants produce fragrant colorful flowers in long spikes. The females produce weird looking pendulous fruits that resemble orange pineapples or oversized pine cones.
There are more than 600 species of screw pines native to the Old World tropics in Asia, Africa and the Pacific. Pandanus utilis hails originally from the continental island of Madagascar, where it commonly grows near the sea. This is the most widely cultivated species in the genus, grown in tropical gardens throughout the world.
Colorful screw pine fruit resembles pineapple in appearance if not in taste.
Culture Light: Grow screw pine in full sun to partial shade. Indoor container plants should be in front of a south or west facing window. Moisture: Screw pine does best in a humid environment, but it is drought tolerant once established. It grows well in any soil, but grows faster and more lush if given plenty of water. Keep moist in summer, but dry in winter and don't let water accumulate in the leaf axils as this can cause rotting. Hardiness: USDA Zones 10-11. Screw pine is strictly a tropical tree. It can be grown outside only in frost-free climates. Indoor plants should be kept above 55°F. Propagation: Propagate screw pine from cuttings or by replanting suckers. Seeds, first soaked for 24 hours, can be planted.
Soil and organic materials are trapped within the screw pine's network of aerial prop roots, a characteristic that makes this species invaluable for stabalizing dunes and coastlines in its native range.
Screw pine is the quintessential tropical tree, dramatic and imposing. No tropical garden should be without this exotic, architecturally fascinating species. Screw pine is very tolerant of salt spray and salty soils, and thus an excellent choice for coastal gardens in tropical climates. Young specimens make interesting container plants, although the smaller P. veitchii is more often used as a house plant. Container specimens need to be kept in a humid environment: Stand the container on a tray of gravel filled with water.
In its native habitat, screw pine, with its many aerial prop roots, is sometimes used for erosion control and to bind sand dunes. The long strap shaped leaves of screw pine are, to this day, used to make mats, baskets and thatched roofs. The fruits are edible.
The screw pines are monocots, more closely related to grasses, bananas and palms than to typical trees (dicots) such as pines or cypresses or oaks.