Red Oak

Quercus rubra L.



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Family:  Fagaceae

Native or Introduced to Illinois:  native 

Natural Habit in Illinois:  rich, upland woods; along river banks; on well drained slopes

Leaf:  Leaves are deciduous, alternate, elliptic, 1025 cm long and 815 cm wide, divided less than halfway to midvein into 711 shallow wavy lobes with a few irregular bristle-tipped teeth, sinuses usually extending less than 1/2 distance to midrib, glabrous and dull green above, light dull green below with tufts of hairs in vein angles.

Flower:  Staminate flowers borne on catkins. Pistillate flowers borne on spikes. Appears with the leaves in April or May.

Fruit:  The fruit is an acorns maturing in the second year, about 1530 cm long, with a broad usually shallow cup, borne singly or in clusters of 25. 

Twig:   The twigs are small, slender, greenish brown to dark brown.

Bark:  On young branches the bark is smooth and gray to greenish.  On the trunk it breaks into long, narrow, shallow ridges flat and smooth on top.  The under bark is light red.

Size/Form/Shape:   A medium-sized to large tree that develops a short trunk and round crown when open grown, straight with a clear bole when grown with competition.

County Distribution Map for Illinois:  


Sources for the Sullivan Middle School Tree Identification Guide were obtained though the use of the following sites:

The information below is from the National Arbor Day Foundation.  This information can be viewed in the original (source) form by visiting The National Arbor Day Foundation at

Sun Exposure:  This oak does well in full sun.
Soil Type:  The Red Oak grows in acidic, loamy, moist, clay, sandy, well-drained soils and is drought tolerant.
Moisture:  Normal moisture with some drought tolerance.
Growth Rate:  This tree grows at a fast growth rate.

Hardiness Zones:  3 - 8
This oak can be expected to grow in the zones shown in color in the zone map.