Mighty hardwoods (4)

I believe the answer is:
oaks
(Other definitions for oaks that I've seen before include "Horse race - trees" , "Soak up with trees" , "Hardwood trees" , "Acorn trees" , "material for shipbuilding" .)
I believe the answer is:
oaks
(Other definitions for oaks that I've seen before include "Horse race - trees" , "Soak up with trees" , "Hardwood trees" , "Acorn trees" , "material for shipbuilding" .)