Identifying Oaks By Their Acorns

Joanne K., Pitt County Extension Master Gardener Volunteer

It's not rain drops falling on our heads these days but acorns! Thanks to an abundant crop this year, acorns are everywhere oak trees are growing — in yards and along sidewalks, streets, roof tops, and nature trails.

These fruits of the oak tree are a vital food source for a variety of birds, mammals, wild turkeys, white-tailed deer, and black bears. After the tannins are boiled out, humans can eat them. Native Americans used acorns for medicinal purposes.

Acorns are one of the ways to identify oak trees, which can be divided into two groups: white and red. White oaks have rounded lobes with no bristles while red oaks have pointed lobes with a fine bristle at the tip.

Acorns are comprised of the nut and the cap (also called the cup). To identify an acorn, look at the cap scale pattern and the nut shape and size. Knowing these characteristics can help in identifying an oak tree just from the acorn.

The sweet-tasting white oak acorns mature in one year. Their caps are shallow with bumpy or warty scales covering less than 1/3 of the nut. The caps are smooth inside.
 
Red oak acorns have a bitter taste and need two years to mature. Their caps are deeper covering 1/3 to more than 1/2 of the nut. The overlapping scales are flat and tight to the nut. The inside of the cap is fuzzy.

Darlington Oak Leaf, Quercus hemisphaerica — Joanne K.

Darlington Oak Acorn, Quercus hemisphaerica — Joanne K.

Darlington Oak, Quercus hemisphaerica - This native evergreen tree in the red oak group has elliptical leaves that are dark green, leathery, and glossy. Its small brown acorns measure about 1/2" long and wide. The light brown shallow cap covers about 1/4 to 1/3 of the nut.

Live Oak Leaf, Quercus virginiana — Joanne K.

Live Oak Acorn, Quercus virginiana —  Lindsay Caesar, Horticulture Department, Clemson University

Live Oak, Quercus virginiana - This long-lived native evergreen in the white oak group has leathery green leaves that are glossy on the upper surface and pale underneath. Its egg-shaped acorns are less than 1" long and wide with a pointed bottom. They're dark brown to black when ripe. The caps are bowl-shaped with tiny sharp-pointed scales covering about 1/3 of the nut.

Nuttal Oak Leaf, Quercus texana - Joanne K.

Nuttal Oak Acorn, Quercus texana -  Joanne K.

Nuttal Oak, Quercus texana - This deciduous oak is in the red oak group. Its 4-8" long leaves are deeply lobed some of which have bristles on the tips. The brown acorns are 1-3" in length and less than 1" in width. Their shallow, thin scaly brown caps cover 1/4 to 1/3 of the nut.

Pin Oak Leaf, Quercus palustris - Joanne K.

Pin Oak Acorn, Quercus palustris - Joanne K.

Pin Oak, Quercus palustris - Pin oak is one of the fastest-growing of the red oaks. Its deciduous leaves are dark green on both sides with sharply pointed bristle-tipped lobes and deep U-shaped sinuses. The young acorn is green maturing to tan. The round nut measures less than 1" long and wide. It can grow singly or in groups of 2-3 nuts. The thin, smooth saucer-shaped cap covers 1/4 to 1/3 of the nut.

Shumard Oak Leaf, Quercus shumardi - Joanne K.

Shumard Oak Acorn, Quercus shumardi? - Joanne K.

Shumard Oak, Quercus shumardi - This deciduous native tree is in the red oak group. The leaves are a shiny dark green on top and pale green with tufts below turning red in the fall. The leaves with pairs of pointed lobes tipped with bristles can be as long as 7 inches. Its brown ovoid-shaped acorns are 1-3" long and wide. The shallow, scaly cap is bowl-shaped covering about 1/3 of the acorn.

Southern Red Oak Leaf, Quercus falcata - Joanne K.

Southern Red Oak Acorn, Quercus falcata - Joanne K.

Southern Red Oak, Quercus falcata - As its name indicates this native, deciduous oak is in the red oak group. It's found in poor soils in eastern NC and tolerates drought and occasional flooding. It has two types of leaves: one with 3-5 irregularly-shaped lobes with bristle tips; the other is pear-shaped with 3 rounded lobes toward the end. They are 5-9" long and 4-5" wide. The oval to round acorn is less than 1" long and wide. Its warty, bowl-shaped cap has hairs covering the top 1/3 of the nut. It's produced as a single or in pairs.

Willow Oak Leaf, Quercus phellos - Joanne K.

Willow Oak Acorn, Quercus phellos - Joanne K.

Willow Oak, Quercus phellos - This deciduous native in the red oak group is frequently found growing near swamps, streams, or canals. The willowy-looking leaves are 4-5" long and 1" wide with bristles at the tip. The leaves are light green above and paler below. The small rounded, brown acorn measures less than 1" long and wide. The cap is scaly and bowl-like and striated with brown and black bands covering about 1/4 of the nut. They are produced as a single or in pairs.

All of these oaks and their acorns can be seen in the Walking Garden at the Pitt County Arboretum. More information about them can be found in the NC Extension Gardener Plant Toolbox at https://plants.ces.ncsu.edu/


More information can be found at:

https://treeidentificationapp.com/blog/how-to-identify-acorn

https://extension.msstate.edu/blogs/extension-for-real-life/how-identify-oak-trees-using-acorns

https://www.fieldbook-app.com/blog/acorn-identification