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17: Fibre plants

Pandanus dubius Spreng.

PANDANACEAE

Pandanus bidur Jungh. ex Miq., Pandanus compressus Martelli, Pandanus pacificus hort.

Knob-fruited screwpine (En). Indonesia: pung (Halmahera), boku (Ternate), haun pantai (Ambon). Philippines: bakong, taboan (Bisaya). Thailand: toei kaeo (Bangkok).

The seacoasts of Peninsular Malaysia, Indonesia (south-western Java, the Moluccas), the Philippines, Papua New Guinea, northern Polynesia and Vanuatu. Also cultivated in this area. Outside this area grown as a potplant or a garden ornamental (known as Pandanus pacificus hort., often trimmed to a certain size, usually remaining sterile).

The very broad and thick leaves are used for coarse weaving, e.g. in Halmahera (Indonesia), the Philippines and New Guinea to make mats. The thick leaves tend to make a springy mat and the waxy epidermis makes them suitable as protection against rain. The leaves are stiff but can be made more flexible by heating them. Fibres from the core of the prop roots are used in Indonesia for tying and plaiting work in chairs. In the northern Moluccas they are popular for making durable thread and rope, in particular fishing lines. In the Bismarck Archipelago (Papua New Guinea) the leaves are used to wrap fish and cassava for baking, and to wrap taro to be softened by being stamped on. They also serve as material for floors and walls and as thatch. Traditionally they were folded into packets for carrying lime for betel chewing. Root fibres are extracted, dried and woven into mats. In the Solomon Islands the leaves are used to cover tobacco during the drying and curing phase, for thatching and to make mats, hats and 'custom umbrellas', durable shields against sun and rain. These shields, 40 cm long and 20 cm wide, consist of Pandanus leaves sewn together with thread, often made from Donax canniformis (G. Forster) K. Schumann. The large seeds of Pandanus dubius are edible and taste like coconut, they are eaten as a relish on Guam. Pandanus dubius is grown as an ornamental.

A dioecious, finally stout, sparingly branched tree, 8—20 m tall with numerous massive prickly prop roots 2—5 m long, but often remaining a rather slow-growing low-rosette shrub; bark brownish, rather smooth. Leaves thick-spongy-coriaceous, 1—5 m x 10—15 cm, rigid toward the base, margins and underside of midrib prickly, outer one-third folded down, veins tessellate with 140—170 parallel secondary veins and conspicuous tertiary cross veins. Male inflorescence a stout raceme 40 cm long, with up to 12 spikes subtended by softly leathery, yellow, boat-shaped, spiny bracts; spike creamy-white, cylindrical, 12—20 cm long, consisting of staminate phalanges 7—14 mm long, with about 6—15 stamens (filaments 1—3 mm, anthers 3—6 mm long) borne subumbellately at apex of a column of 4—6 mm length. Female inflorescence a solitary, globular head, 20—35 cm in diameter, subtended by yellowish bracts; peduncle 60—85 cm long; head composed of 50—90, relatively large carpellate phalanges with 2—5 carpels or of 1-celled drupes, usually a combination of these in one head; ripe carpellate phalange ellipsoid or obovoid, large, 9—13.5 cm x 4—7.5 cm x 4—5 cm, 1—2(—4)-celled, upper one-third free; upper mesocarp solid, 4—7 cm long, consisting of dense parenchyma traversed by longitudinal fibres; lower mesocarp fibrous and fleshy, 3—5 cm long; endocarp 20—35 mm long, hard, thin; stigmas large, often in a row and facing the apex of the syncarp. Seed broad ellipsoid, 10—16 mm long. Pandanus dubius is restricted to rocky coasts, lowland headlands, often in riverine or tidal mangrove swamps, but male plants are apparently rare. It is easy to cultivate, but rarely develops a tall trunk. According to B.C. Stone, Pandanus dubius is classified in subgenus Rykia, section Hombronia.

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[178]Stone, B.C., 1976. The Pandanaceae of the New Hebrides, with an essay on intraspecific variation in Pandanus tectorius. Kew Bulletin 31(1): 47—70.

M. Brink, P.C.M. Jansen & C.H. Bosch

Brink, M., Jansen, P.C.M. & Bosch, C.H., 2003. Pandanus dubius Spreng.. In: Brink, M and Escobin, R.P. (Editors): Plant Resources of South-East Asia No 17: Fibre plants. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea