About Dipteris conjugata Reinw.
Dipteris conjugata Reinw. is a fern species with a long-creeping rhizome that reaches approximately 1 cm (0.4 in) in diameter. The rhizome is covered in black shiny hairs up to 5 mm (0.2 in) long, with coarser hairs on older sections of the rhizome. Its leaf stalks, called stipes, grow at regular intervals along the rhizome, branch three or four times, and can reach up to 2 m (6 ft 7 in) in length. Stipes have hair-like scales at their base and are glabrous toward their upper end. The upper surface of this fern's fronds is green, while the lower surface is glaucous. Fronds measure 35 to 50 cm (14 to 20 in) long, and may grow up to 80 cm (31 in) wide; they are split to the base into two fan-shaped halves, each of which divides an additional three or four times. The ultimate lobes taper to a narrow apex, with deeply or coarsely toothed edges. Main veins branch into two veins multiple times. Numerous small sori grow irregularly scattered across the lower surface of the fronds, with irregular size and shape. These sori lack umbrella-like covers called indusia, and have club-shaped paraphyses, which are filament-like support structures.
This species is native to tropical and temperate Asia, Australia, and some Pacific islands. Its confirmed range includes the Ryukyu Islands of Japan (temperate Asia); Papua New Guinea, Cambodia (mainly Kampot), Singapore, Thailand, Vietnam, China's Hainan, China's Taiwan, India, Indonesia, Malaysia (including the slopes of Mount Ophir), and the Philippines (tropical Asia); Queensland (Australia); and the Pacific islands of New Caledonia and Fiji. Within Thailand, it is found in the provinces of Surat Thani, Phangnga, Nakhon Si Thammarat, Trang and Yala. Within Singapore, it occurs in the districts of Kranji and Tanjung Gul, and on the island of Pulau Tekong.
D. conjugata grows on clay slopes, in clearings, on ridges, and along forest margins. In East Kalimantan, Indonesia, it grows along rivers alongside Nypa Palms. In Borneo, it is commonly found growing with Histiopteris incisa (Thunb.) J. Sm. and Lygodium circinnatum (Burm.) Sw., along forest margins and paths. In New Caledonia, it grows on sunny roadside banks. It is also common on forest margins in high rainfall areas. Its typical altitude range is 500 to 1,200 m (1,600 to 3,900 ft) above sea level in China, 300 to 1,700 m (980 to 5,580 ft) in Malaysia, and 300 to 2,900 m (980 to 9,510 ft) in Singapore. In Singapore, it grows on coastal cliffs at landslide risk.
This species is sometimes planted as an ornamental plant in Singapore. It can grow in poor to well drained soils, and is mostly resistant to disease and pests. Cultivated specimens can be found at Cibodas Botanical Garden in West Java, Indonesia, and in the Fernarium of Universiti Kebangsaan in Malaysia.
D. conjugata has been used as a medicinal plant to treat various ailments. In southern Thailand, its roots are collected for use in traditional medicine. In Fiji, it is used to treat male reproductive ailments. In the highlands of Mindanao, the Philippines, its large fronds are used as umbrellas.
