bur oak

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A deciduous oak tree (Quercus macrocarpa) of eastern North America, having deeply lobed leaves, acorns enclosed within a deep fringed cup, and hard durable wood.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun medium to large deciduous oak of central and eastern North America with ovoid acorns deeply immersed in large fringed cups; yields tough close-grained wood