They are used in Indonesian, Malay and Thai cooking, but not Indian.
They are added to rice as it is cooking, it is boiled with water for a drink, used as a flavouring in desserts, and used as a wrapper for cooking food in.
The leaves come from the “Pandanus amaryllifolius” variety of Screw Pine. The tree has long, thick, dark-green, shiny leathery leaves rather than needles. The leaves, shaped like swords, are about 24 inches (60 cm) long.
In Thailand, they are sold in markets in bunches.
They may be sold frozen in bags in Asian food stores. They are almost never used dried.
In China, the very young leaves of the variety called ” Pandanus tectorius ” are cooked as a vegetable, but when the leaves of this variety get older they’re better as a source of fibre for material to make goods from.
Use only 2 to 3 leaves per dish, simmer with the food, then remove, let cool until safe to handle, then squeeze to get more juice out of them, then discard.
Folk medicine attributes several attributes to Screw Pine Leaves.