Thespesia populnea is a small evergreen tree, typically reaching 6 to 10 meters in height, found widely in coastal areas of the tropics and warm subtropics from sea level up to around 150 meters elevation. It thrives on sandy coastal soils, but grows also on volcanic, limestone, and rocky soils. It grows at a moderate rate, around 0.6 to 1 meter per year for the first few years. The wood of this tree is excellent for carving. Both the fruits and seeds can be dispersed by ocean currents. The tolerance of T. populnea of wind, salt spray, and periodic inundation with brackish water and its ability to thrive in sandy, saline soils make these trees useful as coastal windbreaks. This species is apparently native to coastal areas of the Indian and Pacific Oceans from East Africa and India to mainland Southeast Asia, Indonesia, and the Philippines. However, it now has a pantropical distribution, ranging from the Pacific to the Caribbean and the coast of Africa. (Little and Wadsworth 1964, Whistler 1992; Friday and Okano 2006)
Thespesia populnea is apparently native to coastal areas of the Indian and Pacific Oceans from East Africa and India to mainland Southeast Asia, Indonesia, and the Philippines. Today, however, Thespesia populnea has a pantropical distribution extending from the Pacific to the Caribbean and the coast of Africa. Whistler (1992) notes that this species is found from tropical Africa to Hawaii and on all the high archipelagoes of Polynesia and Micronesia, but only rarely on atolls. Although native in the western part of its range in the Pacific, Whistler suggests that its presence in parts of eastern Polynesia is likely due to ancient introduction by humans. In the Pacific, it is now found from Papua New Guinea and the northern coast of Australia through the Solomons, Vanuatu, and Fiji. In Micronesia it occurs in Guam and the Mariana Islands, Kiribati, Palau, Yap, Chuuk, Pohnpei, Kosrae, and the Marshalls. In Polynesia it is found in Tonga, Samoa, Niue, the Cook Islands, the Society Islands, the Tuamotos, and the Marquesas. (Mueller-Dombois and Fosberg 1998 cited in Friday and Okano 2006; Friday and Okano 2006) This species is also now naturalized in the Americas, where it is found from southern Florida and Bermuda through the West Indies from the Bahamas and Cuba to Trinidad and Tobago, as well as in cultivation in California and from southern Mexico and Belize to Brazil and Chile. (Little and Wadsworth 1964)
In an assessment of the genome sizes of 112 tropical hardwood species belonging to 37 plant families, Ohri et al. (2004) found that Thespesia populnea had the largest genome size (3.32 pg) of those measured in the study.
The somatic chromosome number of Thespesia populnea is 2n=26 (Jarolimova 1994; Das et al. 1995).
Thespesia populneoides, native to the Indian Ocean and first described by Fosberg and Sachet (1972), can be distinguished from T. populnea by its dehiscent (spontaneously opening) fruits, long pedicels (5 to 12 cm versus 1 to 5 cm for T. populnea), and coppery or bronze-colored leaves, which are less deeply cordate than those of T. populnea. The seeds of T. populnea are covered with matted long hairs, while those of T. populneoides have short, erect, bulbous or club-shaped hairs. (Fosberg and Sachet 1972; Friday and Okano 2006) Abedin et al. (2010) provide a useful illustrated comparison between these two species.
Another similar species, the Seaside Hibiscus (Hibiscus tiliaceus), often co-occurs with T. populnea but lacks the rounded and flattened dark brown seed capsules seen in the upper crown of T. populnea. Although, like T. populnea, the Seaside Hibiscus has heart-shaped leaves, T. populnea leaves are narrower than they are long, glossy, and smooth edged, while Seaside Hibiscus leaves are often almost round and are hairy on the underside, sometimes with wavy or toothed edges. (Fosberg and Sachet 1972; Friday and Okano 2006)
Thespesia populnea is a small evergreen tree with a short, often crooked, stem and a broad, dense crown. It has glossy green heart-shaped simple leaves, 6 to 22 cm long, that are alternately arranged. It produces yellow, mostly solitary, many-stamened hibiscus-like axillary flowers. The flowers are 4 to 7 cm long with 5 broad overlapping petals. The petals are pale yellow with a maroon spot at the base of each petal and star-shaped hairs on the outer surface. Individual flowers open and close on the same day and the yellow flowers turn dark red, purple, or pink as the day progresses. The dry, brittle fruits are woody or papery seed capsules, rounded and flattened, containing 5 cells and several seeds. The brown or gray capsules are around 2.5 to 5 cm in diameter and 2 cm tall. Mature fruits are present year-round. They are indehiscent (i.e., do not open spontaneously) but eventually disintegrate, releasing the seeds. When a bud or young fruit is cut, a yellow gummy fluid is exuded. (Little and Wadsworth 1964; Fosberg and Sachet 1972; Whistler 1992; Friday and Okano 2006; Abedin et al. 2010)
In some areas this species is regarded as an invasive weed. It has taken over some beaches used by nesting sea turtles in the West Indies. It serves as a host to several pests of cotton (which is also in the plant family Malvaceae) and as a consequence has been the focus of eradication efforts on some West Indian islands where cotton is an important crop. (Little and Wadsworth 1964; Friday and Okano 2006)
Historically, the fine-grained wood of Thespesia populnea has been used in building boats and furniture, as well as bowls, paddles, gongs, household articles, and handicrafts. Its fibrous bark has been used to make rope. These trees have been planted widely as ornamental, shade, and street trees and as windbreaks and living fenceposts. The seed capsules, wood, bark, and leaves have been used as a source of various dyes. A variety of traditional medicinal uses of these trees have been reported. (Little and Wadsworth 1964; Whistler 1992; Friday and Okano 2006 and references therein)
Based on trials using the Formosan subterranean termite (Coptotermes formosanus), Grace et al. (1996) report that the wood of T. populnea exhibits high resistance to termite feeding.
Thespesia populnea, commonly known as the portia tree (/ˈpɔːrʃə/),[4] Pacific rosewood,[5] Indian tulip tree, or milo, among other names, is a species of flowering plant belonging to the mallow family, Malvaceae. It is a tree found commonly on coasts around the world.[6] Although it is confirmed to be native only to the Old World tropics, other authorities consider it to have a wider, possibly pantropical native distribution.[1] It is thought to be an invasive species in Florida and Brazil.[7][8]
Thespesia populnea is native to tropical coastlines and is adapted for oceanic dispersal and growth in island environments. It is known from both coasts of Africa, 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. Its exact native distribution has been debated, with most authorities considering it to only be native to the Old World tropics,[9] some others such as Plants of the World Online including the Pacific Islands in its native range,[10][11] and others such as the IUCN Red List and the USDA also including the tropical Americas within its native range. The IUCN only considers T. populnea to be introduced and invasive in Florida.[1][12] It may also be invasive in northern Brazil.[8]
Like the related Hibiscus tiliaceus, it was one of the main sources of bast fibers for the production of cordage and wood for Austronesian outrigger ships and carving. Though the plant seeds can survive for months on sea currents, no remains of T. populnea have been recovered from Polynesia prior to the Austronesian expansion (c. 5,000 BP), thus it is regarded by some authors as a canoe plant, deliberately carried and introduced by Austronesian voyagers in the islands they settled.[13][14] However, it is still considered questionably indigenous to the Pacific islands, including Hawaii, by many other authorities.[1][10][11][15] In Hawaii, it is classified as a native species and is used in habitat restoration projects for the degraded Hawaiian tropical dry forests alongside the definitively native tree species Dodonaea viscosa and Cordia subcordata.[16][17][18]
The Portia tree reaches a height of 6–10 m (20–33 ft) tall and its trunk can measure up to 20–30 cm (7.9–11.8 in) in diameter.[19] It grows at elevations from sea level to 275 m (902 ft)[20] in areas that receive 500–1,600 mm (20–63 in) of annual rainfall.[9] The Portia tree is able to grow in the wide range of soil types that may be present in coastal environments, including soils derived from quartz (sand), limestone, and basalt; it favours neutral soils (pH of 6–7.4).[19] Pollen grains are approximately 70 microns in diameter.
The heartwood of the Portia tree is dark reddish brown to chocolate brown and has a specific gravity of 0.55 to 0.89.[9]
Portia tree is known as milo or miro in Polynesian languages. It is popular in Hawaii for woodworking (commonly turned into bowls)[21] because of the range of colours expressed (tan, through yellow, to red). The trees were regarded as sacred in Polynesian culture, and were commonly planted in marae sites along with trees like Ficus, Fagraea berteroana, Casuarina equisetifolia and Calophyllum inophyllum.[13][14] Traditionally it was planted in sacred groves and used for religious sculpture throughout eastern Polynesia. In Tahiti, Milo wood is used in the making of the to'ere (slotted wooden drum), used in traditional Tahitian tribal drumming. Makoʻi was used for the rongorongo tablets of Easter Island.[22] Since the advent of aluminium-hulled boats in the 20th century, Pitcairners have made regular trips to Henderson Island to harvest miro wood. Usually they venture to Henderson only once per year, but may make up to three trips if the weather is favourable. Pitcairners carve the wood into curios, from which they derive much of their income.[23]
In New Ireland, Portia wood is used to make hourglass drums. In Tonga, its bark is used to treat mouth infections among infants, and its wood is used to make canoes, house parts, and artwork.[24]
In South Asia, it is used to make the thavil, a Carnatic musical instrument of South India. The flower of the Portia tree played a part in Sri Lanka's independence movement, when it was sold on Remembrance Day by the Suriya-Mal Movement instead of the poppy to aid Sri Lankan ex-servicemen. The wood from the tree was used by early Tamil people to make instruments in ancient Tamilakam.[25] It can be used for the cellulose production from the plants [Singh et al 2019].
In some parts of the world, such as Hawaii and southern India, T. populnea is considered an important species in habitat restoration projects for coastal dry forests.[16][18][26]
Thespesia populnea, commonly known as the portia tree (/ˈpɔːrʃə/), Pacific rosewood, Indian tulip tree, or milo, among other names, is a species of flowering plant belonging to the mallow family, Malvaceae. It is a tree found commonly on coasts around the world. Although it is confirmed to be native only to the Old World tropics, other authorities consider it to have a wider, possibly pantropical native distribution. It is thought to be an invasive species in Florida and Brazil.
