BUR OAK - Quercus macrocarpa, Michx.
SIOUX CITY, IOWA'S, famous council oak is a majestic bur oak that witnessed Lewis and Clark meeting with the Sioux chiefs in 1803. It was 150 years old when its massive spreading branches sheltered the council and it is still alive.
Bur oak is a strange tree found on two distinctly different soil areas. It grows best in the flood plains of our major streams but it is also one of the few trees to grow on the more moist prairies and plains. Its range extends to the Rockies. It was often a life saver to wagon trains crossing the prairies, being used for wagon tongues, wheel hubs and spokes as well as a welcome relief from buffalo chips as fuel. The leaf is six to ten inches long, alternate, simple and spatula shaped with its broadest width near the end. It is shallowly cleft on the outer half and rather deeply cleft near the base. Above portion is dark green while the under-surface is downy and pale.
A mossy fringe of elongated scales on the edge of the acorn cup accounts for the name mossy-cup which is sometimes given to bur oak. Acorns from bottomland trees are the largest of any oak. They will be from one and one-half to two inches long and are about half-closed by their cup. Prairie bur oak acorns are only three-fourths of their length.
Corky, thick twigs are a key identifying feature which can be seen even from the ground. This is the only oak with this thick corky bark on the twigs. The buds are egg-shaped.
Bark on the trunk is gray-brown. It is thick and deeply ridged at maturity.
Lumber from this species is used for all of the same products made from white oak lumber except veneer.
