Family : Malvaceae
Text © Pietro Puccio
English translation by Mario Beltramini
The species is native to Bhutan, Borneo, Cambodia, India, Java, Laos, Lesser Sunda Islands, Moluccas, Myanmar, New Guinea, Peninsular Malaysia, Singapore, Sumatra, Thailand and Vietnam where it lives in the forests of Dipterocarpaceae, often on slopes close to water streams, from the sea level up to about 1200 m of altitude.
The name of the genus comes from the combination of the Greek substantives “πτερόν” (pteron) = wing and σπέρμα” (sperma) = semen, with obvious reference; the name of the species is the Latin adjective “javanicus, a, um” = of Java, with reference to one of its places of origin.
Common names: bolang (Bali); bayur, bayur laki, bayur merah (Borneo); balang, cerlang, wadang (Java); bayor, letop-letop, litak, (Malaysia); nwa-labyin (Myanmar); bangero, buli, lero (Sulawesi); bayok (Philippines); bayur, bayur burung, cemerlang, merilang (Sumatra).
The Pterospermum javanicum Jungh. (1840) is an evergreen tree up to more than 50 m tall in the old specimens in nature, with erect trunk, of up to about 1 m of diameter, often provided at the base of tabular roots (flat roots similar to buttresses) up to 2 m tall, and brown-greyish bark that with the time tends to fissure and flake off.
The leaves, on a 0,4-0,6 cm long tomentose petiole, are alternate, simple, ovate with pointed apex, asymmetrical base and entire margin, waved or toothed, often peltate in the young plants, of glossy green colour above, covered by white brownish tomentum below, 5-14 cm long and 3-7 cm broad.
The stipules, thin, pointed, about 1 cm long, present at the base a small cup with the inner surface covered by pearly glands that attract the ants.
Inflorescences, on a 1-1,5 cm long peduncle, axillar or subterminal with 1-3 hermaphroditic flowers, of about 10 cm of diameter, with linear sepals with pointed apex, 5-6,5 cm long and 0,5 cm broad, yellowish white and covered externally by pale brown tomentum, 5 oblong-spatulate petals, white, 3-3,5 cm long and 3-4 cm broad, and pentalocular superior ovary. The fruits are fusiform woody capsules, 5-12 cm long and of 3-4 cm of diameter, covered by a rust coloured tomentum, dehiscent from the apex to the base in five lodges, containing numerous seeds provided on a side with a long wing that favours the dispersion by means of the wind. It reproduces by seed, that does not have a long lasting germinability, in draining loam maintained humid at the temperature of 24-26 °C.Fast growing species cultivable in tropical and subtropical regions in full sun, excepting the first years of life where it is necessary a slight shade, that shows a remarkable adaptability concerning the soil, as it can grow on humid soils, but without stagnations, as well as on the dry, clayey or sandy ones. It has a certain economic importance for the wood, commercially known and exported with the name of “bayur”, of good quality, average hardness and density, easy to work and to refine, utilized locally in the constructions of the dwellings, for beams, floors, fixtures and coatings, of boats, bridges, furniture, art objects, in the veneer (technique consisting in covering a low-quality wood with thin wood sheets) and in the fabrication of the plywood. The bark is used in the traditional medicine of the local populations for various pathologies.