Nypa fruticans

The nipa palm, or mangrove palm, is the only palm species that thrives in the mangrove biome. It grows along coastlines and in estuaries across the Indian and Pacific Oceans. Because it is the sole member of both the genus Nypa and the subfamily Nypoideae, these groups are considered monotypic.

Description

Unlike most palms, the nipa palm’s trunk grows underground. Only the leaves and flower stalks rise above the surface, with leaves reaching up to 9 meters tall. The flowers form a round cluster: female flowers at the tip and catkin-like red or yellow male flowers on lower branches. These produce woody nuts arranged in a round cluster up to 25 centimeters across on a single stalk.

The entire fruit cluster can weigh as much as 30 kilograms. Each seed has a fibrous husk that helps it float. As the fruits mature, the stalk droops, and the ripe seeds separate and drift away on the tide, sometimes germinating while still in the water.

Biology

The nipa palm is the only palm adapted to the mangrove biome. Old leaf bases expose internal tissue that allows air to reach the submerged roots, functioning like the pneumatophores of other true mangroves. As leaves develop, the leaf base swells with spongy tissue connected to air-filled networks in the roots. When leaves die, only the rachis falls off; the base, filled with protective tannins, stays alive for up to four years.

Ecology

Small insects pollinate the nipa palm. Putative pollinators include Drosophilidae flies, Trigona bees, Apis florea (Asian dwarf honey bee), Apis dorsata (Asian giant honey bee), nitidulid and curculionid beetles. Long-tailed macaques eat the fruits. Proboscis monkeys in the Padas Damit Forest Reserve have been seen eating the inflorescences.

Bornean orangutans eat the palm hearts and shoots. The fungi Tirisporella beccariana and Phomatospora nypae (the latter found on palms in Malaysia) have been recorded on the mangrove palm. Several lepidopteran species use it as a host plant, including skippers (Erionota thrax, Gangara thyrsis, Hidari irava), crambids (Herculia nigrivitta, Nacoleia octasema), pyralids (Tirathaba leucotephras, Tirathaba mundella, Tirathaba rufivena), a tineid (Erechthias flavistriata), and limacodids (Parasa corbetti, Parasa lepida).

Fossil record

Today, only one species of Nypa exists—N. fruticans—with a natural range from northern Australia through the Indonesian Archipelago and the Philippines to China. But the genus once had a nearly global distribution during the Eocene (56–33.4 million years ago). Fossil pollen from India dates to 70 million years ago.

Fossil fruits and seeds have been found in Maastrichtian and Danian sediments of Egypt’s Dakhla Formation. Eocene fossilized nuts occur in sandbeds in Dorset, England, and in London Clay on the Isle of Sheppey, Kent. A fossil species, N. australis, comes from Early Eocene sediments at Macquarie Harbour, Tasmania.

Fossils have also been recovered across North and South America, from the Maastrichtian through the Eocene, with the last American appearances in the late Eocene. If extinct Nypa lived in habitats similar to the modern species, its fossils may indicate monsoonal or seasonal rainfall and tropical climates. The Eocene’s worldwide Nypa distribution, especially at polar latitudes, supports evidence that the Eocene was a time of global warmth before modern polar icecaps formed.

Nipa palms grow in soft mud and slow-moving tidal and river waters that bring nutrients. They can be found as far inland as tides carry the floating nuts. They are common along coasts and rivers flowing into the Indian and Pacific Oceans, from India to the Pacific Islands. The palm survives occasional short-term drying but is only moderately salt tolerant and suffers in pure seawater, preferring brackish estuarine waters.

It is native to China (Hainan), the Ryukyu Islands, Bangladesh, the Indian subcontinent, Sri Lanka, the Andaman and Nicobar Islands, Vietnam, Laos, the Malay Peninsula (north of Singapore), all of Borneo, Java, Maluku, the Philippines, Sulawesi, Sumatra, the Bismarck Archipelago, New Guinea, the Solomon Islands, the Caroline Islands, and Australia (Queensland and the Northern Territory). It has become naturalized in Nigeria, the Society Islands of French Polynesia, the Mariana Islands, Panama, and Trinidad. Japan’s Iriomote Island and neighboring Uchibanari Island mark the northernmost limit of its range.

The long, feathery leaves are used locally for thatching roofs and in basketry. Because the stems are buoyant, they are used to train swimmers in Burma. On the islands of Roti and Savu, nipa palm sap is fed to pigs during the dry season, reportedly giving the meat a sweet flavor. Young leaves are dried, bleached, and used for other purposes.