The leaves are starting to fall off the big bur oak tree in my back yard. The drought this summer has caused them to drop earlier than usual. Soon I will be raking thousands of leaves and removing them from the roof’s rain gutters. During the hot months this summer I greatly appreciated the large one hundred year old oak tree on the south side of my house. Its massive limbs and large leaf canopy provided dense shade for the entire house that helped reduce the cost of air-conditioning. The tree also provides beauty to the yard as the leaves change color during the seasons. The leaf buds are a light green color when they unfold in the spring. In summer the leaves are dark green and change to bronze in the fall.
The tree has given other forms of enjoyment too. It is the home and way station for many creatures in our yard. Squirrels chase each other around the trunk and feed on the acorns the tree produces. All year nuthatches can be seen looking for insects in the deep furrowed bark and last spring a robin made a nest in the fork of a branch. The tree was also a place for my daughters to play; it was home base for one of the games of tag.
The oak family is divided into two groups; the “white oaks” have smooth rounded lobes on their leaves and their acorns mature in one year. This group contains the species of white oak, bur oak, and swamp white oak. The “red oaks” have pointed lobed leaves and their acorns take two years to mature. Examples in the red oak group are red oak, black oak, and pin oak. Bur oak makes a strong and durable lumber; it is grouped with white oak lumber. It is used for making furniture, flooring, interior trim, boats, tool handles, and barrels.
In 1961 the Iowa General Assembly chose the oak tree as Iowa’s official state tree. But no particular species was designated. I would vote for the bur oak tree, Quercus macrocarpa. It can grow in almost every Iowa soil type, from damp bottomlands to dry hilltops. The bur oak tree is the dominate tree that forms the savannas on Iowa’s prairies. It flowers in the spring and the acorns mature at the end of the growing season. The tree gets its name from the hairy fringe around the cup of the acorn. The tree does not begin to flower and fruit until it is about thirty years old. The bur oak is a tree that has adapted to growing in the prairie sod. It has a taproot that grows six to ten inches before the first leaves appear. The taproot will grow five to six feet deep in the first growing season; this allows the tree to absorb subsoil moisture during times of drought. The tree’s thick bark allowed it to withstand the fires that used to be common on the Iowa prairie. A former owner of my house planted my bur oak in 1902. Now the tree is over fifty feet tall and has a circumference of more than ten feet. It has me doing a lot of leaf raking in the fall, but it is worth it. The bur oak tree provides shade and beauty; it is a great asset.