Hibiscus populneoides Roxb.

Thespesia populnea is a shrub or medium-sized evergreen tree, up to 20 m tall with a dense crown. Bark greyish. Twigs densely covered with brown to silvery scales, glabrescent. Leaves alternate, simple; petiole 5-8 (max. 16) cm long; stipule lanceolate to subulate, 3-10 mm long, scaly; blade orbicular, deltoid, ovate or oblong, 7-23 x 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 scalelike bracts near the base. Calyx campanulate, subtruncate, 12-14 mm long, 18 mm in diameter, densely adpressed 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 x 4.5-6 cm. Fruit a globose capsule, 2-4.5 cm in diameter, faintly 5-angular, 5-celled, apex obtuse or slightly depressed, with disclike calyx at the base of the young fruit, usually indehiscent, exuding a bright yellow gum when cut. Seeds 4 per cell, obovoid, 8-15 x 6-9 mm, slightly angular, covered by closely matted silky hairs. The generic name is based on the Greek word ‘thespesios'-divine, supposedly because T. populnea was frequently planted round temples. The specific name means looking like the popular tree.

Trees flower and fruit throughout the year. The yellow flowers open about mid-morning, turning reddish-orange in the afternoon, then fading to pink on the tree and not falling off for several days. Pollination is probably by birds. The seed floats in sea water, making natural distribution by sea currents possible.

Soils are sandy, slightly alkaline and poor in nutrients.

T. populnea is pantropic along sea coasts, often in locations where sandy beaches covered by Casuarina equestifolia give way to coral outcrops and in Barringtonia vegetation. The species can also be found on rocky coasts such as in Malaysia. T. populnea is only sparingly found on the inland edge of mangrove persisting from cultivation. It is a suitable tree for dry locations and is highly tolerant of saline conditions.

T. populnea probably originates from the Asiatic tropics and now occurs throughout the tropics.

The tree can be easily raised from seeds or cuttings. Raising from seed is preferred as then the timber is knot free, straight, even grained and tough. Cuttings of all sizes strike well, but it is preferable to plant small cuttings as trees raised from large cuttings are said to be short lived and liable to decay. The cut end is usually pasted with cow-dung slurry. Direct sowings are generally a failure.

In India, growth of T. populnea is reported as rapid. The leaves are lopped for fodder.

T. populnea is one of the alternative hosts of a number of serious cotton pests, such as the cotton stainer (Dysdercus sp.) and cotton-boll weevil (Anthonomus grandis). 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.

Seed storage behaviour is orthodox.

Erosion control: Because of its tolerance of saline conditions, T. populnea is suitable for coastal erosion control, and it is planted for this purpose in Karnataka, India. Soil improver: Leaves are used for green manure. Wood chippings have also been tried as a green manure. Ornamental: In many parts of the Pacific, T. populnea is a sacred tree, often planted near temples. Elsewhere, it has been planted as an ornamental and roadside tree. Boundary or barrier or support: In mangrove areas, T. populnea is often planted to consolidate ridges and bunds in an aquasilvicultural system for prawn production.

Food: Young flower buds and leaves are eaten raw or fried in butter. Fodder: The leaves are a good source of protein, calcium and phosphorus for livestock. Fibre: Bark yields a strong fibre used for cordage, fishing lines, coffee bags and for caulking boats. Timber: The fine-grained, strong, hard and durable wood is 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 wood of Thespesia is light to medium in weight with a density of 400-770 kg/m³ at 15% mc. 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. Used for horse-drawn carts and wheelbarrows, to carve canoe paddles, bowls, plates and utensils. It is resistant to insect attack. Tannin/dyestuff: The wood and the yellow gum from the fruit and flowers yield a dye, and the bark produces tannin. Medicine: The heartwood has a healing property useful in treating pleurisy and cholera, colic and high fevers; it is carminative. The cooked fruit crushed in coconut oil provides a salve, which, if applied to the hair, will kill lice. The sap of the leaves and decoctions of most parts of the plant are used externally to treat various skin diseases. Juices from the pounded fruits mixed with pounded leaves are ingredients of a poultice to treat headaches and itches. A decoction of the astringent bark is used to treat dysentery and haemorrhoids, and a maceration of it is drunk for colds. The fruit contains an antibiotic and the juice is used to treat herpes. Other extracts of the plant have significant antimalarial activity. Leaf and bark decoctions are taken for high blood pressure. Leaf tea is taken for rheumatism and urinary retention. Seeds are purgative.