Thespesia populnea (L.) Sol. ex Corrêa

Scientific Name and Size

The Portia tree, Thespesia populnea (L.) Sol. ex Corrêa, reaches a height of 6–10 m (20–33 ft), with a trunk diameter of up to 20–30 cm (7+3⁄4–11+3⁄4 in).

Pollen Characteristics

Its pollen grains are approximately 70 microns in diameter.

Native Habitat Adaptations

Thespesia populnea is native to tropical coastlines, adapted for oceanic dispersal and growth in island environments.

Global Distribution Range

It occurs on both coasts of Africa, in tropical Asia, northern Australia, the Pacific Islands including Hawaii, the tropical Pacific coast of the Americas from Mexico south to Colombia, the West Indies, and Florida in the United States.

Native Range Debate

Its exact native range is debated: most authorities consider it native only to the Old World tropics, some sources including Plants of the World Online include the Pacific Islands in its native range, and sources such as the IUCN Red List and the USDA also include tropical America in its native range.

Invasive Status

The IUCN only classifies T. populnea as introduced and invasive in Florida, and it may also be invasive in northern Brazil.

Traditional Austronesian Uses

Like the related Hibiscus tiliaceus, it was one of the main sources of bast fiber for cordage production and wood for Austronesian outrigger ships and carving.

Canoe Plant Hypothesis

Although the plant's seeds can survive for months on sea currents, no remains of T. populnea have been recovered from Polynesia prior to the Austronesian expansion around 5,000 BP, so some authors regard it as a canoe plant, deliberately carried and introduced by Austronesian voyagers to the islands they settled.

Pacific Indigenous Status Debate

However, many other authorities still consider it questionably indigenous to Pacific islands, including Hawaii.

Hawaiian Restoration Use

In Hawaii, it is classified as a native species, and is used in habitat restoration projects for degraded Hawaiian tropical dry forests, alongside the definitively native tree species Dodonaea viscosa and Cordia subcordata.

Elevation and Rainfall Requirements

It grows at elevations from sea level to 275 m (902 ft) in areas that receive 500–1,600 mm (20–63 in) of annual rainfall.

Soil Preferences

It can grow in a wide range of soil types found in coastal environments, including soils derived from quartz (sand), limestone, and basalt, and it favors neutral soils with a pH of 6–7.4.

Heartwood Characteristics

The heartwood of the Portia tree is dark reddish brown to chocolate brown, with a specific gravity of 0.55 to 0.89.

Polynesian Common Names

Portia tree is called milo or miro in Polynesian languages.

Hawaiian Woodworking Use

It is popular in Hawaii for woodworking, and is commonly turned into bowls, due to its range of colors from tan through yellow to red.

Polynesian Cultural Significance

The trees were regarded as sacred in Polynesian culture, and were commonly planted in marae sites alongside trees such as Ficus, Fagraea berteroana, Casuarina equisetifolia, and Calophyllum inophyllum.

Eastern Polynesia Religious Use

It was traditionally planted in sacred groves and used for religious sculpture throughout eastern Polynesia.

Tahitian Musical Instrument Use

In Tahiti, Milo wood is used to make the to'ere, a slotted wooden drum used in traditional Tahitian tribal drumming.

Easter Island Rongorongo Use

Makoʻi wood from this species was used for the rongorongo tablets of Easter Island.

Henderson Island Harvesting

Since aluminum-hulled boats were introduced in the 20th century, people from Pitcairn Island have made regular trips to Henderson Island to harvest miro wood.

Pitcairn Harvest Frequency

They usually travel to Henderson only once per year, but may make up to three trips if the weather is favorable.

Pitcairn Curio Production

Pitcairners carve miro wood into curios, which provides much of their income.

Hawaiian ʻUmeke Cultural History

In Hawaiʻi, ʻumeke (Hawaiian for "wooden bowl") has been a highly perfected art form, and ʻumeke have been considered prized possessions for well over a thousand years, especially those made of Milo and Kou, because these dense hardwoods do not add flavor to food.

Pre-1819 Hawaiian ʻUmeke Restrictions

Before 1819, ʻumeke were considered sacred and strictly reserved for ʻAliʻi (Hawaiian royalty), and commoners faced the death penalty for possessing one.

Modern Hawaiian ʻUmeke Significance

Today, ʻumeke are highly collectible and have become known as a universal symbol of generosity and welcome.

New Ireland Drum Use

In New Ireland, Portia wood is used to make hourglass drums.

Tongan Medicinal and Craft Uses

In Tonga, its bark is used to treat mouth infections in infants, and its wood is used to make canoes, house parts, and artwork.

Indonesian Culinary Use

In Indonesia, this species is known as baru laut, baru pantai or waru lot, and people from Ambonese cook its leaves into a vegetable dish.

South Indian Musical Instrument Use

In South Asia, its wood is used to make the thavil, a Carnatic musical instrument of South India.

Sri Lankan Independence Movement Role

The flower of the Portia tree played a role in Sri Lanka's independence movement: it was sold on Remembrance Day by the Suriya-Mal Movement instead of the poppy, to support Sri Lankan ex-servicemen.

Ancient Tamil Instrument Use

Early Tamil people used the tree's wood to make instruments in ancient Tamilakam.

Cellulose Production Use

It can be used for cellulose production from the plant (Singh et al. 2019).

Global Restoration Significance

In some parts of the world, such as Hawaii and southern India, T. populnea is considered an important species for coastal dry forest habitat restoration projects.