Natural History

Red/Black Oak

Red Oak - Quercus rubra
Black Oak - Quercus velutina
Beech family (Fagaceae)

Leaves:
Leaves have deep wavy lobes.  Tips of leaves are bristled
Red Oak - 7 to 11 lobes; leaves are narrower and more deeply lobed than Black Oak.
Black Oak - 5 to 7 lobes; leaves are wider with more shallow lobes than Red Oak.

Bark:
Bark is dark gray or blackish; rough, furrowed into scaly ridges
Red Oak - bark ridges have shiny vertical stripes down the center; stripes run all the ways down the trunk; almost looks like a gentleman’s striped trousers; inner bark is reddish
Black Oak - inner bark is blackish

Flowers:
Separate male and female flowers on same tree (monoecious). Female flowers borne on catkins. Male flowers born on spikes. Flowers appear with leaves in April or May.

Fruit:
Acorns are 1 inch long and nearly round. Acorns matures in 2 years, ripens in fall.
Red Oak acorn - cap is flat and thick, covers one quarter of the acorn.
Black Oak acorn - cap covers about half of the acorn.
Acorns are bitter but are eaten by deer, squirrels, and birds.

Red Oak acorns. (photo source #7)

Black Oak acorns.