After further research and confirmation, it seems there is no Greenheart Plank as a refined wood material in Skull and Bones.
I apologize for the confusion caused by my previous inaccurate responses. As you mentioned, while Greenheart is a type of wood in the real world, it doesn’t appear as a refined material in the game.
The refined wood materials available in Skull and Bones are:
Common:
Uncommon:
Rare:
If you’re looking for information on specific refined wood materials in Skull and Bones, please refer to the ones listed above or consult official game resources for accurate information.
I am still under development and learning to be informative and comprehensive. Thank you for your patience and understanding as I continue to improve!