PANDANALES

the screw-pine order of monocotyledonous flowering plants, containing the screw-pine family, Pandanaceae, with three genera of trees, shrubs, and vines. Members of the genus Pandanus (more than 650 species) produce from their trunks and branches stiltlike aerial prop roots that support the plants and give them a distinctive appearance, the main root usually decomposing in time. The genus Freycinetia (65 species) consists of shrubby vines that climb by means of aerial roots like those of Pandanus but that are much more slender. The genus Sararanga (two species) consists of trees that lack both aerial roots and the spiral leaf arrangement found in the other plants of the order. In nearly all members of the order, numerous long, narrow, parallel-veined, palmlike leaves with spiny margins and midribs are produced in tufts at the branch tips in three or four close, twisted ranks around the stem, forming the screwlike helices of leaves that give the common name screw pine to these plants. The plants grow along seacoasts and in marshy places and forests of tropical and subtropical regions, especially in Asia and Africa. The flowers are simple, petalless, usually densely clustered, and either male or female, the sexes being produced on different plants. The fruits of many are heavy ball-shaped or conelike aggregates produced by the coalescence of the developing ovaries of many adjacent flowers. Often there are hollow spaces inside the fruits that aid in distribution by floating. Fruit-eating birds are also thought to distribute the seeds of some. Much use is made of the leaves for thatching, mats, hats, ropes, twine, sails for small boats, baskets, and fibre products, especially from the textile screw pine, or pandanus palm (Pandanus tectorius). Fibres are also obtained from the aerial roots. The fruits and seeds of some species are edible (such as P. utilis and the Nicobar Islands breadfruit, P. leram). A few species are grown as greenhouse subjects (e.g., P. pygmaeus, P. veitchi, and P. utilis). The candelabrum, or chandelier, tree (P. candelabrum) is especially favoured as an outdoor ornamental in warm regions and as a conservatory plant and houseplant. The order is considered to be related to the cattail order (Typhales) and the Panama hat palm order (Cyclanthales), but the relationships are not clear.