People and Plants of Micronesia

Casuarina equisetifolia – Casuarinaceae

Common name: Casuarina, she oak, ironwood, beefwood

Ngas, nas, ngasu (Pl-Mad refer to as C. littorea), Nach, noc (Yap), lach (Ulithi), laash (Woleai), Gago (Guam), Weeku (C, PU), Te burukam, Te katurina, Te katuarina  (KI), bûlukam, mejinoki, nidõl, pientri (Marshall), weku (Pohnpei)        


Description: A tall pine-like tree with a soft, wispy apprearance that grows up to 20-30m (65-100 ft) in height, which is known in English as "ironwood" or "she-oak,” and “horesetail tree." The leaves are reduced to rings of scales around long, slender, grooved, branches that are somewhat like pine needles. Flowers are unisexual, found on the same or separate trees.  Its flowers are tiny, brown and wind-pollinated. The fruit is a nutlet about ½ inch in diameter that contains winged seeds. The fruits are small, brown, and cone-like.

Trees 10-20 m tall; branches long, slender, the tips drooping, pubescent.  Leaf sheaths with (6)7(-9) teeth. Staminate spikes densely flowered, 1-6 cm long, bracts densely pubescent.  Cones subglobose to elongate and oblong-globose, 1.2-2.2 cm long, ca. 1.1-1.4 cm in diameter, the valves broadly ovate, protruding ca. 2 mm, pubescent, apex obtuse.  Nuts 6-7 mm long.  A pioneer, salt-resistant tree.  Very hardy on both limestone and volcanic soils.  (Found in: )

It is a nitrogen fixing tree and used for erosion control on coastal areas.

“It has a very hard, heavy, dark red-brown wood, hence one of the common names, ironwood. In the past, its wood was used extensively for making house parts, posts, fish hooks, and various other tools and artifacts”. Found in (Elevitch, 2006)  Traditional Trees of Pacific Islands.

“Because it is very strong and needs little processing, it is ideal for posts and rough house construction. It is also useful for fencing, piling, and roofing shingles. The rapid growth of the tree and the fine quality fuelwood it produces (it is one of the best firewoods in the world) makes it excellent for use in fuelwood plantations, its main commercial importance today, especially in Asia and Africa.” Found in (Elevitch, 2006)  Traditional Trees of Pacific Islands.

“The tree is important culturally since its bark is widely used in traditional medicines for treating digestive tract problems and other ailments.” Found in (Elevitch, 2006)  Traditional Trees of Pacific Islands.


Ecology: Swearingen (1997) states that C. equisetifolia is fast-growing (1.5 to 3 metres per year), produces dense shade and a thick blanket of leaves and hard, pointed fruits, that completely cover the ground beneath it. Dense thickets displace native dune and beach vegetation, including mangroves and many other resident, beach-adapted species. Once established, it radically alters the light, temperature, and soil chemistry regimes of beach habitats as it outcompetes and displaces native plant species and destroys habitat for native insects and other wildlife. Chemicals in its leaves may inhibit the growth of other plants underneath it. The ground below the tree becomes ecologically sterile, reducing the food value for native wildlife. Unlike native shrubbery, the thick, shallow roots make it much more susceptible to blow-over during high wind events, leading to increased beach and dune erosion and interference with the nesting activities of sea turtles and American crocodiles. Elfers (1988) reports that Casuarina also poses a problem to humans because it is a source of respiratory irritation. Its pollen can cause allergic reactions symptomized by eye irritation, runny-nose, and hoarseness or sore throat.


Distribution: An introduced species to most Pacific Islands.  This tree, with very strong wood, is widespread from Australia to various islands in the Pacific. Although it is common on seacoasts and capable dispersal by ocean currents this tree was probably an ancient human introduction to many islands, and most likely is a relatively recent introduction to [Yap]. It can be propagated by planting cuttings.The seeds have a membranous wing and are wind-dispersed (Binggeli 1997).

Found across Australia and into Melanesia, Micronesia and Polynesia; widely cultivated and naturalized in tropical and subtropical regions. Probably an ancient introduction to Polynesia (Whistler, 1992). Either native to Melanesia and Micronesia or an early introduction. (Found in: )

This tree occurs in open, coastal strand habitat, characterized by sand and shell beaches, rocky coasts, sand dunes, and sand bars in subtropical climates.  (Found in:  NPS fact sheet.  2005. )

“Modern introduction to Hawai‘i and probably Micronesia and, in more recent times, throughout the tropics, where it is now one of the most common trees on beaches, fernlands, and other inland areas of poor soil.”  Found in (Elevitch, 2006)  Traditional Trees of Pacific Islands




For Pohnpei: “To make as a glue or paint, as many fruits as needed are cut in half, then the nuts are taken out, scraped, and mixed with a type of red soil (that can only be found as Nanpwoarenais, Madolenihmw), then put in a pot over a fire and stirred until it turns into a thick red liquid…The resin is used to make paint to coat the inside of canoes…To used as a natural mosquito coil, as many fruits as needed are put into a fire so the smoke produced drives the mosquitoes away……The wood is used for lumber [Yosio Pelep: MB4139]. The wood is also used to make house posts…To treat diarrhea and amoebic dysentery…To treat a rash…To treat a rash on a baby’s leg…” (Pg. 349)


For Palau: “The wood is used for building poles, handicrafts and as fuel. Although the wood is very hard, it is difficult to work with and therefore not desirable for carving or timber. Medicinal uses include the following: the bark for toothaches and digestive track problems, the inner bark for teeth, and the roots for treating asthma. Ngas can be very invasive, especially in poor soils and marginal habitats. It grows quickly in degraded and infertile areas, and can be used for soil erosion control, windbreaks and to stabilize coastal sands. However, it can be harmful in areas of native vegetation. The needles inhibit the growth of other plants.”


 The inner bark is used for terminating pregnancy and the roots are used to treat asthma (Salsedo et al, 1987). 


For Guam: “In Guam it is scarcely at all utilized, as it is hard to work. In Guam it is abundant along sandy beach, especially on the east shore of the island. It also grows on the high ‘sabanas,’ where it is usually the only tree, but it never grows within the forest. All the Guam trees have twisted and gnarled trunks, from the effects of hurricanes” (Safford, 220). “Its common name is Polynesian ironwood” (Safford, 220).

Its hard wood is used for construction and for firewood.  It is also known to have some medicinal uses.  (Found in:  Guam Forestry Nursery Plants, 2006-see pdf.


For Chuuk: Although use of Weeku is limited in Chuuk, this woody plant was traditionally used in some areas of the Pacific as a source of very strong wood for war clubs.  Its inner bark is also used on some Polynesian islands for treating sore throats and other ailments.  On Puluwat axe handles and some canoe parts are made from the wood of this tree.


For Yap:  In Yap (Ulithi), the inner bark is used to treat diarrhea and other digestive tract ailments.  Found in (Elevitch, 2006)  Traditional Trees of Pacific Islands.


For Kiribati: “Increasingly common in villages and in reclaimed areas; introduced as a potential source of timber and fuelwood; useful as a windbreak on ocean side of islets to protect newly planted coconuts” (Thaman, 24). A.R.B. No. 333

Catala (1957: 76) referred to C. equisetifolia as plants used as building material for housess, canoes, fishing rods, etc. “Only 3 Casuarina trees were seen in the whole area visited. Two were young plants 1.8 m tall in the garden of the Residency at Bairiki on Tarawa, and had been planted in July 1951 (brought from Australia). The third, said to have been planted by Americans during the war is on Butaritari and is a straight fine tree about 10 m tall and 30 cm in diameter, about 7 years old. It grows near a group of houses. It is surprising that this tree is not more abundant on these islands, as on so many others in the Pacific. It could profitably be planted on shores not used for coconuts” (Catala, 1957:88).

I have been told that in Kiribati people would tie the tip of a branch of the ironwood to itself and allow it to grow into the shape of a fishhook.  When it reached appropriate size a fishhook would be carved out of it.