Pandanus spiralis

Pandanus spiralis is a small tree in the family Pandanaceae native to northern Australia. It is commonly called pandanus, spring pandanus, screw palm or screw pine, although it is neither a palm nor a pine.

Description
Pandanus spiralis is a small tree growing up to 10 m tall with a slender trunk, and often with a clumping habit. Prop roots may be present, but are more often absent. The leaves are 1–2 m long and 4–7 cm wide, and they may or may not have sharp spines along the leaf margins and midrib. They are arranged spirally on the trunk and branches, and crowded towards their tips. As the leaves die they can form a dense pendant skirt around the trunk below the growing part, and lower down on the trunk the leaf bases often persist, forming a conspicuous spiral.

The inflorescences are terminal—on the male plants it is a pendant string of several spadices each about 5 cm long, while on the female plants it is a single head about 20–30 cm long shrouded by large leafy bracts.

The fruit is a multiple fruit consisting of 10–25 segments measuring 8–10 cm long and 5–8 cm wide, known as "phalanges". The phalanges are composed of a dense fibrous material with 5–7 seeds embedded in it. The fruit is initially green and turn orange or red when ripe.

Taxonomy
This species was first described by the Scottish botanist Robert Brown in his book Prodromus floræ Novæ Hollandiæ et Insulæ Van-Diemen, published in 1810.

Infraspecies
Five varieties are recognised, as follows:
 * Pandanus spiralis var. convexus (H.St.John) B.C.Stone – synonyms P. convexus H.St.John and P. integer H.St.John
 * Pandanus spiralis var. flammeus B.C.Stone
 * Pandanus spiralis var. multimammillatus B.C.Stone
 * Pandanus spiralis var. spiralis – autonym
 * Pandanus spiralis var. thermalis (H.St.John) B.C.Stone – synonym P. thermalis H.St.John

Distribution and habitat
This species occurs in northern Queensland, the Northern Territory and the extreme north of Western Australia. It grows in savannah woodlands and poorly drained areas such as alongside creeks and rivers, the margins of floodplains, and coastal dunes, on various substrates including sand, alluvium and clay.

Ecology
The dense skirt of old leaves provides a refuge for many forms of wildlife including birds, bats, rodents and lizards. The seeds within the fruit are eaten by cockatoos and possums.

Uses
The leaves of this tree are used to weave various products such as neckbands, armbands, baskets, mats, fish traps and shelters, and the fibre can be stripped out to make string for dillybags and other uses. The trunks are used to build rafts. The plant has a number of medicinal uses including as an antiseptic, analgesic, and to treat dysentery and diarrhoea.. The white stem part of the leaf is pounded to make an anaesthetic for tooth pain. The leaf bases are eaten and the seeds can be eaten raw or roasted, and may be ground to make flour. The fully ripe fruit are used ceremonially because of their scent.