Economic Botany of Timbers in North East India Topic: Hollong (Dipterocarpus retusus) and Semal (Bombax ceiba)

 

 


1. Hollong (Dipterocarpus retusus)

Dipterocarpus retusus (syn. D. macrocarpus), commonly known as Hollong, is a majestic hardwood and the State Tree of both Assam and Arunachal Pradesh. It belongs to the family Dipterocarpaceae (Grow-Trees, 2026).

A. Distribution

●       Regional Range: In North East India, it is primarily distributed across the alluvial deposits of the Brahmaputra valley, particularly in Upper Assam, Arunachal Pradesh, and Nagaland (Thakur et al., 2002).

●       Habitat: It thrives in moist evergreen to semi-deciduous montane forests at altitudes ranging from 100 m to 1500 m. It prefers well-drained, acidic red laterite soils (CABI Compendium, 2020; Thakur et al., 2002).

B. Parts Used and Method of Use

●       Timber (Bole): The tree produces a clean, cylindrical commercial bole reaching up to 40-50 meters (Thakur et al., 2002).

○       Construction: Used for beams, joists, door/window frames, and heavy-duty flooring (CABI Compendium, 2020).

○       Plywood Industry: It is the premier raw material for the plywood industry in North East India due to its favorable anatomical characters (Thakur et al., 2002).

●       Oleoresin (Dammar/Dhoona): Tapped from the bark.

○       Industrial: Used in varnishes, lacquers, and as a waterproofing agent (World For Nature, n.d.).

○       Cultural/Medicinal: Burned as incense and used in traditional medicine for its antiseptic properties (Grow-Trees, 2026; World For Nature, n.d.).

C. Nutritive and Chemical Value

While not a primary food source, the tree possesses significant chemical constituents:

●       Phytochemicals: The oleoresin contains triterpenoids and essential oils.

●       Ecological Contribution: As a dominant rainforest giant, it supports high carbon sequestration, with studies in the Barak Valley showing it contributes up to 94.3% of total aboveground carbon stocks in certain forest stands (ResearchGate, 2015).


2. Semal (Bombax ceiba)

Bombax ceiba, known as the Red Silk Cotton Tree or Ximolu (Assamese), belongs to the family Malvaceae (formerly Bombacaceae). It is a fast-growing deciduous tree characterized by a prickly trunk and vibrant red flowers (Wikipedia, 2026).

A. Distribution

●       Regional Range: Widely distributed across North East India’s alluvial plains and riverine tracts. It is a common feature of the deciduous forests and savanna woodlands of Assam (CABI Compendium, n.d.; Wikipedia, 2026).

●       Habitat: It grows best in deep sandy loams or young alluvial soils found in valleys, tolerating annual rainfall from 50 cm to 460 cm (IP Int J Compr Adv Pharmacol, 2022).

B. Parts Used and Method of Use

●       Timber: The wood is soft, light, and creamy white.

○       Match Industry: Primary wood used for match splints and boxes (CABI Compendium, n.d.).

○       Plywood & Packaging: Used for low-grade plywood, tea chests, and packing cases (CABI Compendium, n.d.).

●       Fruit (Kapok): The capsules contain white silky fibers.

○       Bedding: Carded and used to stuff pillows, quilts, and mattresses (Wikipedia, 2026).

●       Flowers:

○       Culinary: In North East India and neighboring regions (like Myanmar and Thailand), the fleshy calyx and dried flowers are cooked as a vegetable or used in spicy soups (Wikipedia, 2026).

●       Bark and Roots: Used in traditional "Ayurvedic" and tribal medicine as a tonic for sexual health, dysentery, and as an anti-inflammatory paste (IP Int J Compr Adv Pharmacol, 2022).

C. Nutritive Value

●       Phytoconstituents: Contains naphthols, naphthoquinones, polysaccharides, anthocyanins, shamimin, and lupeol (Der Pharma Chemica, n.d.).

●       Dietary Value: The flowers are rich in minerals and antioxidants. Seeds contain edible oil (though mostly used for biodiesel or soap) and are high in protein (RJPT, 2020).

●       Medicinal Nutrition: The gum (Mocharas) is used as a demulcent and tonic to treat malnutrition-related debility (Der Pharma Chemica, n.d.; RJPT, 2020).

References

●       CABI Compendium. (2020). Dipterocarpus retusus. https://doi.org/10.1079/cabicompendium.19740
Cited by: 12

●       CABI Compendium. (n.d.). Bombax ceiba (silk cotton tree). https://doi.org/10.1079/cabicompendium.9499

●       Der Pharma Chemica. (n.d.). Bombax ceiba Linn: An ethnopharmacological update. https://www.derpharmachemica.com/pharma-chemica/bombax-ceiba-linn-an-ethnopharmacological-update-90072.html

●       Grow-Trees. (2026). Hollong: Northeast India's towering rainforest giant. https://www.grow-trees.com/blog-individual/520/hollong

●       IP International Journal of Comprehensive and Advanced Pharmacology. (2022). Bombax ceiba plant. https://ijcap.in/archive/volume/7/issue/1/article/3312

●       ResearchGate. (2015). Assessment of aboveground and soil organic carbon stocks in Dipterocarpus forests of Barak Valley, Assam, Northeast India. https://www.researchgate.net/publication/282764077

●       Research Journal of Pharmacy and Technology (RJPT). (2020). Review on traditional uses, biological activities, phytoconstituents of Bombax ceiba Linn. https://rjptonline.org/HTMLPaper.aspx?Journal=Research%20Journal%20of%20Pharmacy%20and%20Technology;PID=2020-13-11-93

●       Thakur, S. K., et al. (2002). An early assessment of Dipterocarpus retusus progeny trial. https://vafs.gov.vn/en/2006/09/an-early-assessment-of-dipterocarpus-retusus-progeny-trial/

●       Wikipedia. (2026). Bombax ceiba. https://en.wikipedia.org/wiki/Bombax_ceiba

●       World For Nature. (n.d.). Assam ST - Hollong (Dipterocarpus retusus). https://worldfornature.org/assam-st/

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