Oak tree

Oak is a term used to refer to around four-hundred separate species in the genus Quercus (Latin for "Oak Tree"), native to the northern Hemisphere of Earth. The White Oak is a notable member of the genus. Historically, they have been used in a variety of ways, from ship building to wine aging, and when the first Human colonies were started, the first settlers saw fit to bring the Oak Tree to several new planets, quite possibly for its strength and resistance to attacks from insects and fungi.

In the Halo Universe

Oak Wood was brought along to the colony of Madrigal, where it was considered "very rare". Ignatio Delgado's uncle saw fit to carve the modified stock for Señora Sies out of the wood.

References

There is more information available on this subject at Oak tree on the English Wikipedia.