2076

7: Bamboos

Dendrocalamus membranaceus Munro

Trans. Linn. Soc. 26: 149 (1868).

GRAMINEAE

2n = 72 (hexaploid), 70

Waya (En). Burma (Myanmar): waya, wamu, wapyu. Laos: s'a:ng, hôk hnhaix. Thailand: phai-sangnuan, phai-nuan, phai-sangdoi (northern).

Dendrocalamus membranaceus is native to Thailand (especially northern and northeastern), Burma (Myanmar) (eastern and down to Tenasserim) and Laos. It is occasionally cultivated in its native area and has been introduced in many botanical and private gardens (e.g. in Indonesia (Bogor, Lampung) and in India (Kerala)).

Culms of Dendrocalamus membranaceus are used for building purposes, bamboo board, furniture, basketry, matting and handicrafts, and as props for fruit trees. They are said to be very promising for the production of paperpulp. Young shoots are edible; they have a slightly bitter taste but are excellent for processing because they are nearly smooth and easy to handle. When administered to hamsters, the aerial part of the plant induced anti-implantation activity.

Dendrocalamus membranaceus is produced and traded locally in its native area. No statistics are available.

At a moisture content of 102.5% green culms have a density of 551 kg/m³; dry culms have a density of 664 kg/m³ at 7.2% moisture content. The fibre length is 2—3(—4.5) mm. At culm moisture contents of 102.5% and 7.2% the modulus of elasticity is 2393 N/mm² and 3697 N/mm², the modulus of rupture 25.8 N/mm² and 37.1 N/mm² and the compression strength parallel to grain 39.7 N/mm² (no data for 7.2%) respectively. The average fresh weight of young shoots is 1167 g and the edible portion is about 40%. After cooking, shoots are creamy-white and tender.

Sympodial bamboo, forming rather open clump. Culm very straight, 20—24 m tall, 6—10 cm in diameter, wall 6—10 mm thick, covered with white powdery deciduous scurf when young, turning green on maturity; internodes 22—38 cm long; nodes prominent, basal ones with aerial roots. Branches arising from all nodes, upper ones slender and drooping. Culm sheath 30—50 cm x 12—20 cm, glabrous or with appressed dark brown hairs; blade narrowly lanceolate, 25—40 cm x 2—3 cm, reflexed, brown hairy on both sides; ligule about 5 mm long, dentate; auricles dark brown, wavy, fringed. Leaf blade lanceolate, 12—25 cm x 1.5—2.5 cm, thin, pale, hispid above, hairy on the midrib beneath, margins scabrous, apex acuminate; sheath striate, ending in a callus, cleft nearly to the base; ligule very short, obtuse, hairy; auricles falcate, wavy-bristly, 1 cm long, purplish ciliate, very white hairy when young. Inflorescences on leafless branches, consisting of distant globular spinescent heads 2.5—5.0 cm apart and up to 2.5 cm in diameter; spikelet slightly compressed, 10—13 mm x 2—5 mm, glossy, nearly glabrous, with 2 empty glumes and 2—3 fertile florets. Caryopsis broadly ovoid, 5.0—7.5 mm long, grooved on one side and somewhat flattened, ending in a sharp point.
Dendrocalamus membranaceus sheds its culm sheaths very early. It flowers gregariously, in Thailand between October and April (dry season), but a flowering cycle is not known. In India it flowered in a botanical garden at an interval of 20 years.
Dendrocalamus membranaceus resembles glabrous forms of Dendrocalamus strictus (Roxb.) Nees and may easily be mistaken for it. It can be distinguished from the latter by its glabrous spikelets, thinner leaves, culm sheath with wavy hairy auricles, recurved apical leaf, and the more elongate grooved caryopsis.

The natural habitat of Dendrocalamus membranaceus is a tropical mixed deciduous or monsoon forest below 1000 m altitude. In northeastern Thailand (Tak), where Dendrocalamus membranaceus is native, annual average minimum temperature is 21.7°C (14.5°C in January, 25.6°C in April) and average maximum temperature 33.3°C (30.5°C in December, 38.1°C in April); the average annual rainfall is 950 mm with a dry season from November to April.

Dendrocalamus membranaceus can be propagated by seed and by rhizome and culm cuttings. Fresh seed has a germination percentage of 90%. Seed remains viable for quite a long period (60% germination after 6 months); if stored at 4—5°C, germination percentage was 80% after 6 months. Propagation by tissue culture is promising but still in the experimental stage. Planting is done in the rainy season. Young plants need watering in the dry season. No serious diseases or pests are known. The culms are rather resistant to culm borers but not to fungi. For construction purposes fully mature, 3—4-year-old culms are harvested, for basketry 2-year-old culms are used. Culms with the largest diameters are preferred for the bamboo board industry. After harvesting, culms are traditionally submerged in running water for 10—20 days. Preservation by boiling culms for 10—20 minutes in a solution of sodium carbonate, calcium hydroxide and copper sulphate is also practised. It takes about 3 months to air dry the culms. Mature culms dry with little cracking, immature ones are liable to collapse and shrink excessively. Culms used for weaving and handicrafts are cleaned by rubbing with ash, coconut husks or rice straw, which leaves the shiny surface undamaged; sandpaper cleaning is used for furniture. For furniture making, culms are roasted above fire at 110—130°C for 15—20 minutes 2—3 times.

A germplasm collection of Dendrocalamus membranaceus is available at the Centre bamboorium of Arunachal Pradesh in India. More collections are urgently needed from its native areas. There are no breeding programmes.

Most of Dendrocalamus membranaceus resources in natural forests have been overexploited for many decades. Given the increasing demand for culms for local uses, studies on proper methods for cultivation, harvesting, and conservation are urgently needed. Dendrocalamus membranaceus is potentially of interest for the production of edible shoots in other South-East Asian countries.

Aswal, B.S., Bhakuni, D.S., Goel, A.K., Kar, K., Mehrotra, B.N. & Mukherjee, K.C., 1984. Screening of Indian plants for biological activity: part 10. The Indian Journal of Experimental Biology 22: 312-332.
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Chunwarin, W., 1985. Culm structure, composition and physical properties of bamboos. Proceedings of the bamboo seminar, 6-7 June 1985, Kasetsart University, Bangkok. pp. 157-198.
Sanyal, S.N., Gulati, A.S. & Khanduri, A.K., 1988. Strength properties and uses of bamboo. A review. The Indian Forester 114: 637-649.
Smitinand, T. & Ramyarangsi, S., 1980. Country report Thailand. In: Lessard, G. & Chouinard, A. (Editors): Bamboo research in Asia. Proceedings of a workshop held in Singapore, 28-30 May 1980. International Development Research Centre, Ottawa, Canada, and the International Union of Forestry Research Organizations, Vienna, Austria. pp. 85-90.
Tewari, D.N., 1992. A monograph on bamboo. International Book Distributors, Dehra Dun, India. pp. 68-70.
Vongvijitra, R., 1990. Traditional vegetative propagation and tissue culture of some Thai bamboos. In: Ramanuja Rao, I.V., Gnanaharan, R. & Sastry, C.B. (Editors): Bamboos current research. Proceedings of the international bamboo workshop, November 14-18, 1988, Cochin, India. The Kerala Forest Research Institute, India and International Development Research Centre, Canada. pp. 148-150.

S. Duriyaprapan & P.C.M. Jansen

Duriyaprapan, S. & Jansen, P.C.M., 1995. Dendrocalamus membranaceus Munro. In: Dransfield, S. & Widjaja, E.A. (Editors): Plant Resources of South-East Asia No 7: Bamboos. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea