- Editor’s Note: “Roadside Botany” is a snapshot look at the amazing plant life that can be found in Kane County, IL, with photography and text by Valerie Blaine, nature programs manager for the Forest Preserve District of Kane County. You can reach her at firstname.lastname@example.org.
This fall has been a banner year for leaf-lovers. Colorful foliage lingered long into November, giving us lots of time to “ooh!” and “ahh!” at the trees. Among the beauties in the fall pageantry are the oaks.
There are nine different kinds of oaks in Kane County. Like fine wine, they fall into two groups: whites and reds. The groups share some similarities that can help you identify them.
First, look at the outline of the leaf. Trees in the white oak group have rounded lobes. Trees in the red oak group have lobes with pointed tips. This is a pretty good rule to go by, and it will get you into the ballpark of oak i.d. Once you know the general group, the next step is to determine which white oak, or which particular red oak it is.
This is where it can get confusing. Within the general white oak group, there are several species. For starters, there’s THE white oak, Quercus alba. This species has the classic oak leaf shape that is often used as a logo.
White oak leaves are about 10 inches long and 5 inches wide, with seven to nine lobes. In autumn white oak leaves turn a beautiful red color. They have been spectacular this year, setting treetops ablaze with color.
A close cousin to the white oak is a bold-looking species called bur oak. It’s got rounded lobes – so it’s in the white oak group, but this one goes by Quercus macrocarpa. The leaves of bur oak are wide at the end, and narrow at the base near the twig. The lobes at the end have narrow indentations; those near the twig have deep indentations. Overall, the leaf is about 14 inches long – quite a bit bigger than white oak.
Now look at those oaks with pointed-tip leaves. These are in the general red oak group, but there’s a specific northern red oak, Quercus rubra. This one has leaves up to 10 inches long, with seven to 11 lobes.
The fall of 2016 has been lit up by the intense scarlet color of the northern red oak leaves. It’s been one of the best red oak seasons I’ve ever seen.
Also in the red oak group are black oaks and pin oaks. Pointed tips, but different lobes. Black oak leaves have seven to nine lobes with shallow indentations. If you look on the underside of a black oak leaf, even a brown crinkled leaf in winter, you’ll see some “fuzz.” There’s a slight hairiness to black oak leaves.
Pin oaks (Quercus palustris) have five to seven lobes with indentations that go way in towards the central vein. The tops of pin oak leaves are shiny, but there may be some small hairs underneath.
“But what if there are no more leaves on the trees?” people often ask. “Then how do you tell the oaks apart?” And, the next question is usually “Why do some oaks hold onto their leaves all winter?” Good questions … Stayed tuned!
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About the Forest Preserve District of Kane County
The Forest Preserve District of Kane County acquires, holds and maintains land to preserve natural and historic resources, habitats, flora and fauna. The district restores, restocks, protects and preserves open space for the education, recreation and pleasure of Kane County citizens. For more information, visit the district’s website or find them on social media via Facebook, Twitter or Instagram. Also, sign up for the quarterly TreeLine Newsletter.
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