Bira

The Bira Tree (ビラ, Bira) are a type of tree that is found mostly within the NGL and its substance is a main ingredient to the narcotic D².

Background
The NGL holds 80% of Bira Tree in its country and its main use is to produce a narcotic drug known as D², in its narcotics factory.

Chimera Ant arc
Kite and his team of Gon and Killua, locate a narcotics factory that produces the narcotic D². Kite mentions that the substance from the Bira Tree is the main ingredient for D².