The following species of Agarwood produce Agarwood:
1. Aquilaria acuminata, found in Papua New Guinea, Indonesia & Philippines.
2. Aquilaria apiculata, found in the Philippines
3. Aquilaria baillonil, found in Thailand and Cambodia
4. Aquilaria banaensae, found in Vietnam
5. Aquilaria beccariana, found in Indonesia
6. Aquilaria brachyantha, found in Malaysia
7. Aquilaria crassna is found in Cambodia, Malaysia, Thailand, Laos and Vietnam.
8. Aquilaria cumingiana, found in Indonesia and Malaysia
9. Aquilaria filaria, found in New Guinea, Moluccas, and Mindanao (Philippines)
10. Aquilaria grandiflora, found in China
11. Aquilaria hirta, found in Thailand, Indonesia and Malaysia
12. Aquilaria khasiana, found in Bangladesh and India.
13. Aquilaria malaccensis, found in Indonesia, Malaysia, Laos, Thailand and India
14. Aquilaria microcarpa, found in Indonesia and Malaysia
15. Aquilaria rostrata, found in Malaysia
16. Aquilaria sinensis, found in China and Laos
17. Aquilaria subintegra, found in Thailand
18. Sri Lankan "Agarwood" is called Walla Patta and belongs to the species Gyrinops walla.
Basically, a lot of trees have a scent like sandalwood, frankincense ... it is not agarwood (oud), Oud is made by the one of the 18 types of species trees listed, they are very biologically diverse. In the early stages, agarwood trees are light white color when it is injured by insect, they will produce resin to protecting,this resin changed the color of tree from yellow color to black color..
After a period from a few years to a few decades, the resin will produce a fragrance, some types can be up to a hundred years. That is the best fragrance what was finding by everyone in the world.