Pandanus is a genus of over 600 species worldwide with about 30 occurring in Australia where they are found in tropical and sub-tropical areas. They are dioecious shrubs or trees (male and female plants) with stems that are much-branched and with aerial roots present, usually in the form of prop roots.
Pandanus tectorius is a small tree which can reach 5-6 metres in height comprising separate male and female trees. The leaves are linear to about 1 metre in length by 5-8 cm wide with sheathing bases. They emerge from the branches in a screw-like arrangement which gives rise to the common name. The leaves have short spines along the edges and on their midribs. The plants are supported at the base by prop roots which help to anchor the plant in sandy soil. The flowers occur in clusters surrounded by large bracts and plants may flower throughout the year. Female plants produce large pineapple-like fruits comprised, when ripe, of yellow, red or orange segments containing the individual seeds.
Parts of the fruit of P. tectorius are edible and it is reported to form a major source of food in Micronesia. The ripe segments of the fruit and the seeds can be roasted and eaten.
There are several varieties recognised but P.tectorius var. australianus and P.tectorius var. pedunculatus are the only ones listed in the Australian Plant Name Index for Australia. The taxonomic status of other varieties is uncertain.
Screw pine is a hardy plant for tropical, sub-tropical and warm temperate areas where frost is not a problem. It can be grown in most well drained soils in a sunny location and is tolerant of exposed coastal situations.
Propagation can be carried out from seed collected from the woody segments of the fruit (which may take up to a year to ripen). Seed does not require pretreatment prior to sowing. Large stem cuttings can also be used for propagation by selecting stems with some aerial roots attached.
Pandanus tectorius: Growth habit
Photo: Murray Fagg – Australian National Botanic Gardens
Pandanus tectorius: Fruit
Photo: Brian Walters