Q.Describe the timber-yielding plants of Assam with their scientific names and uses, and explain the special importance of Hollong.

See the detailed account.

1. Teak — Tectona grandis (Lamiaceae): very durable, termite- and water-resistant wood; premier furniture and shipbuilding timber (grown in Assam as a plantation tree).
2. Sal — Shorea robusta (Dipterocarpaceae): hard, heavy, strong structural timber for beams, posts and railway sleepers; native to the North-East foothills.
3. Sissoo (Shisham) — Dalbergia sissoo (Fabaceae): strong, decorative rosewood for furniture, veneer and carving.
4. Gomari (Gamhar) — Gmelina arborea (Lamiaceae): light, stable, easily-worked wood for plywood, matchwood, carving and pulp; common throughout Assam.
5. Hollong — Dipterocarpus retusus (syn. D. macrocarpus), (Dipterocarpaceae): a giant rainforest tree (up to ~60 m) of Upper Assam, prized for plywood and construction.

Special importance of Hollong: it is the State Tree of Assam, a defining tree of the state's wet-evergreen rainforests (e.g. Dehing Patkai). Because it is listed as Endangered on the IUCN Red List, its felling is now restricted and it is a focus of conservation.