Thespesia populnea (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Thespesia populnea (L.) Soland. ex Corrêa

Protologue: Ann. Mus. Hist. Nat. Paris 9: 290 (1807).

Family: Malvaceae

Chromosome number: 2n = 24, 26, 28

Synonyms

• Hibiscus bacciferus J.G. Forster,
• Hibiscus populneus L. (1753)
• Malvaviscus populneus (L.) Gaertn.
• Thespesia macrophylla Blume (1825)
• Hibiscus populneoides Roxb. (1832).

Vernacular names

• Milo, Pacific rose-wood, portia tree (En). Cork tree, seaside mahoe, milo (Hawaii) (Am).
• Indonesia: baru laut (general), salimuli (Moluccas), waru lot, waru laut (Javanese)
• Malaysia: baru, baru-baru (general), baru laut, bebaru (Sarawak)
• Philippines: banalo (Tagalog), tuba-tuba (Bikol), balu (Sulu).
• Cambodia: baëhs sâmut(r), chréi sâmut(r).
• Thailand: po kamat phrai (south-western), pho-thale (central).

Origin and geographic distribution

T. populnea probably originates from the Asiatic tropics but now it occurs throughout the tropics. It is fairly common all along the shores of South-East Asia, and is also cultivated further inland.

Uses

In mangrove areas, T. populnea is often planted to consolidate ridges and bunds in an aqua-silvicultural system for prawn production. In Karnataka (India), it is planted along the coast as protection against erosion. The fine-grained, strong, hard and durable wood is highly priced furniture wood, and is also used for light construction, flooring, moulds, musical instruments, utensils and vehicle bodies. As it is very durable under water, it is popular for boat building. The bark is much used for caulking and making ropes. Chippings have been tried as a green manure. The young leaves are eaten as a vegetable. The wood and the yellow gum from the fruits and flowers yield a dye. The corewood is used in medicines against colic and fever. The leaves and fruit are applied to cure skin diseases, while the ripe fruit, pounded with coconut oil, provides a cure against lice. In many parts of the Pacific, T. populnea is a sacred tree, often planted near temples. Elsewhere, it is also grown as an ornamental and roadside tree.

Properties

The fruits yield 0.4% of a flavonoid colouring matter; while thespesin, ceryl alcohol and beta-sitosterol have been isolated from the unsaponifiable fraction of the seed oil. Gossypol is present in the flowers and bark. Plant extracts have significant anti-malarial activity. The wood of Thespesia spp. is light to medium-weight with a density of 400-770 kg/m³ at 15% moisture content. The heartwood is dark red and smooth. Its texture is medium to fine. Shrinkage upon seasoning is very low to low. The wood seasons well. It is easy to saw and work despite its wavy grain.

Botany

• Shrub to medium-sized, evergreen tree, up to 20 m tall with dense crown. Bark greyish. Twigs densely covered with brown to silvery scales, glabrescent.
• Leaves alternate, simple; petiole 5-8(-16) cm long; stipules lanceolate to subulate, 3-10 mm long, scaly; blade orbicular, deltoid, ovate or oblong, 7-23 cm × 5-16 cm, apex acuminate, base generally cordate, sinus deep and narrow, rather fleshy and shiny, palmately 7-veined, in the axils of the basal veins beneath mostly with saccate nectaries, main veins yellow.
• Inflorescence a large, solitary, axillary flower; pedicel 2.5--8 cm long, erect or ascending, sometimes articulate with 2 scale-like bracts near the base, at apex with a discoid hypanthium 6-8 mm in diameter; epicalyx segments 3, oblong to lanceolate, 4-17 mm × 2 mm, caducous, subcoriaceous, acute, densely scaly
• Calyx campanulate, subtruncate, 12-14 mm long, 18 mm in diameter, densely appressed hirsute within, scaly, glabrescent outside; corolla broadly campanulate, up to 6 cm long and wide, pale yellow with dark purple centre; petals 5, obliquely obovate, 6-7 cm × 4.5-6 cm, apex rounded; stamens many, monadelphous, staminal column glabrous, filaments about 4 mm long, anthers about 1.5 mm long; ovary globose to ovoid, 8-10 mm in diameter, scaly, 10-celled, style about 4 cm long; stigmas connate to clavate, pale yellow.
• Fruit a globose capsule, 2-4.5 cm in diameter, faintly 5-angular, 5-celled, apex obtuse or slightly depressed, with disk-like calyx at the base of the young fruit, usually indehiscent, exuding a bright yellow gum when cut.
• Seeds 4 per cell, obovoid, 8-15 mm × 6-9 mm, slightly angular, covered by closely matted silky hairs.

The yellow flowers open at about 10 a.m. in the morning, turning reddish-orange in the afternoon, then fading to pink on the tree and not falling off for several days.

Some authors recognize the specimens occurring along the coasts of the Indian Ocean as a distinct species: T. populneoides (Roxb.) Kosteletsky, having somewhat bronzed or coppery, shallowly cordate to subtruncate leaves, pedicel 5-12 cm long, drooping, a dehiscent outer layer of the fruit and seeds with short clavate or bulbous hairs. However, many intermediate specimens exist, called "hybrids" by some, occurring where both forms can be found. In Sri Lanka some of these "hybrids" have been widely propagated vegetatively as ornamentals and living fences.

Ecology

T. populnea is found on coasts throughout the tropics, often in locations where sandy beaches covered by Casuarina equisetifolia L. give way to coral outcrops and in Barringtonia vegetations. In Malaysia, it is also found on rocky coasts. It does not occur in mangroves. The seed floats in sea water, making natural distribution by sea currents possible. T. populnea is only sparingly found on the inland edge of mangrove or persisting from cultivation. It is a suitable tree for very dry locations.

Agronomy

Propagation is by seed or stump cuttings. T. populnea is prone to fungal root and butt rot caused by Phellinus noxius. This is characterized by slowly enlarging diseased patches and a thick, dark brown mycelial sheath around the base of infected trees. T. populnea is one of the alternative hosts of a number of serious cotton pests, such as cotton stainer (Dysdercus spp.) and cotton boll weevil (Anthonomus grandis).

Genetic resources and breeding

No germplasm collections and breeding programmes are known to exist.

Prospects

Because of its tolerance to saline conditions T. populnea is suitable for planting to control beach erosion. Its similarity to Hibiscus tiliaceus L. suggests that it deserves testing as a wind-break.

Literature

• Fosberg, F.R. & Sachet, M.H., 1972. Thespesia populnea (L.) Solander ex Correa and Thespesia populneoides (Roxb.) Kosteletsky (Malvaceae). Smithsonian Contributions to Botany 7: 1-13.
• Lahiri, A.K., 1987. Silvipisciculture as land management system for rural development in mangrove areas. Indian Agriculturist 31: 305-311.
• Morton, J.F., 1976. Craft industries from coastal wetland vegetation. In: Wiley, M. (Editor): Estuarine processes. Vol. 1. Uses, stresses and adaptation to the estuary. Third International Estuarine Research Conference, Galveston, Texas, United States, October 7-9, 1975. Academic Press, New York, United States. pp. 254-266.
• Nakanishi, H., 1988. Dispersal ecology of the maritime plants in the Ryukyu Islands, Japan. Ecology Research 3: 163-174.
• Parrott, W.L., McKibben, G.H., Robbins, J.T. & Villavaso, E.J., 1989. Feeding response of the boll weevil (Coleoptera: Curculionidae) to ester extracts of host plants. Journal of Economic Entomology 82: 449-453.
• Patil, A.S. & Kulkarni, Y.S., 1981. A new bacterial leaf spot disease of Thespesia populnea Sol. ex Corr. Current Science 50: 1040-1041.
• van Borssum Waalkes, J., 1966. Malesian Malvaceae revised. Blumea 14: 105--119.
• Vasanth, S., Gopal, R.H. & Rao, R.B., 1990. Plant anti-malarial agents. Journal of Scientific and Industrial Research 49: 68-77.

Authors

• A. Latiff & I. Faridah Hanum