Dicranopteris linearis (Burm.) Underwood
|Common Names:||Resam, Bengkawang|
Also known locally as 'Resam', this native species of fern is large (< 3 m). It has a characteristically forking stem that grows horizontally at ground level with stalked fronds that are compound. The main rachis is divided dichotomously into two rachis branches, which also fork further about 3–4 times. At the end of the upward-growing, forked frond, there are two ultimate leafy branches of equal lengths (width= 9–12 cm) which are deeply, pinnately lobed and comb-like.
The sporangia, where spores are produced and stored, are also found at the underside of the lobes of the ultimate two branches. The sporangium lacks indusia whereas the spores are trilete.
There is also another similar native species in Singapore (Dicranopteris curranii) which is also known as Resam, but D. curranii differs by having two ultimate branches of unequal lengths and are narrower in width (6 cm).
Bukit Batok Nature Park, Bukit Timah Nature Reserve, Central Catchment Nature Reserve, Jurong Road, Kent Ridge Park, Labrador, Pulau Senang, Singapore Botanic Gardens, Southern Ridges
This hardy species can grow well in nutrient-depleted soils. It is very common in Singapore and is usually found growing in forest edges, gaps and more open areas of forests.
For an account of the life history of a fern, see Pyrrosia piloselloides.
They tend to form pure stands of thick, dense thickets. Once established, they are difficult to clear, thus making it very difficult for seedlings of other forest trees to grow and restore gaps and open spaces in forests. Clearing the dense thickets of Resam requires burning.
The Arabs used to make pens using the stipe of this fern, thus gave rise to its common name 'resam' which means 'to delineate' in Arabic.
The stems of this fern can be woven together to make mattings, fish-traps, chair seats, walls, pouches, caps, and ropes.
The plant is also used for medicinal purposes, being made into a poultice, and infusions and decoctions for fever. However, due to the arsenic content in the plant, large doses of resam is not advised as it is harmful to humans.
Chong, K. Y., H. T. W. Tan & R. T. Corlett, 2009. A Checklist of the Total Vascular Plant Flora of Singapore: Native, Naturalised and Cultivated Species. Raffles Museum of Biodiversity Research, National University of Singapore, Singapore. 273 pp.
Johnson, A. , 1977. The Ferns of Singapore Island. Singapore University Press, Singapore. 128 pp.
Piggott, A. G. 1988. Ferns of Malaysia in Colour. Tropical Press Sdn. Bhd., Malaysia. 458 pp.
Tan, H. T. W. 2011. Resam. p431. In: Ng, P. K. L., R. T. Corlett & H. T. W. Tan (editors). Singapore Biodiversity. An Encyclopedia of the Natural Environment and Sustainable Development. Editions Didier Millet, Singapore. 552 pp.
Wee, Y. C. 1983. A Guide to the Ferns of Singapore. Singapore Science Centre, Singapore. 72 pp.