USA Official State Tree of Iowa

Bur Oak

(Fagaceae Quercus macrocarpa) Recognized
Adopted in 1961.


Although Iowa did not designate a specific species of oak as its state tree, many people recognize bur oak,Fagaceae Quercus macrocarpa, as the state tree since it is the most widespread species in the state.

The Oak was designated as the official state tree in 1961. The Iowa Legislature chose the Oak because it is abundant in the state and serves as shelter, food, and nesting cover for many animals and birds.

It is difficult to find a tract of natural woodland in Iowa that does not harbor at least one species of Oak. No other group of trees is more important to people and wildlife. Acorns, the nuts of Oak trees, are a dietary staple of many animals and birds. Wild turkeys, pheasants, quail, wood ducks, raccoons, squirrels, chipmunks, bluejays, nuthatches, grackles, and several kinds of woodpeckers are a few of the species that depend on acorns for a significant portion of their diet.

The mighty, majestic oak has, throughout the centuries, been the subject of story, song and proverb. More than 80 species of this beautiful tree are found in North America. All oaks are deciduous trees with toothed leaves and heavy, furrowed bark. The fruit is, of course, the acorn. Like other deciduous trees, most oaks shed their leaves in fall. However, in warmer areas of the continent, some varieties, the ?live' oaks, keep their greenery throughout the winter. Oaks have always been economically important for their hard, strong wood which has a multitude of purposes including furniture and flooring. Oaks also have landscape uses although mature trees can dominate smaller sites.

  • Leaf: Alternate, simple, 6 to 12 inches long, roughly obovate in shape, with many lobes. The two middle sinuses nearly reach the midrib. The lobes near the tip resemble a crown. Pale pubescence is present below.
  • Flower: Male flowers are green, borne in naked catkins, 2 to 4 inches long. Female flowers are reddish and appear as single spikes. Appearing shortly after the leaves.
  • Fruit: Acorns are quite large (1 1/2 inches long) and 1/2 enclosed in a warty cap that has a long-fringed margin. Maturing in one year, dropping August to November.
  • Twig: Quite stout, yellow-brown in color, with corky ridges. Multiple terminal buds are small, round, and may be somewhat pubescent. Small, horny stipules are generally present. Laterals are similar, but smaller.
  • Bark: Ashy gray to brown in color and quite scaly, but noticeably ridged vertically.
  • Form: A medium-sized to large tree that is very coarse in appearance. Develops a very spreading, broad crown.


Taxonomic Hierarchy
Kingdom Plantae -- Plants
Subkingdom Tracheobionta -- Vascular plants
Superdivision Spermatophyta ? Seed plants
Division Magnoliophyta ? Flowering plants
Class Magnoliopsida ? Dicotyledons
Subclass Hamamelidae ?
Order Fagales ?
Family Fagaceae ? Beech family
Genus Quercus L. ? oak
Species Quercus macrocarpa Michx. ? bur oak


Dendrology at Virginia Tech
U.S. Department of Agriculture