During the second half of October, my attention is often on tree leaves during my walks in Detroit’s Eliza Howell Park. Recently I collected a leaf each from some of the oak trees that grow in the park and made a small photo collection.
Oak leaves rarely have brilliant Fall colors. My attention is, instead, on the variety of oaks present.
There are dozens of different oak species native to Eastern North Anerica, but it is usually not necessary to know the precise species of an individual tree. As long as I can accurately place it in one of the two major groups of North American oaks (the Red Oaks and White Oaks), I know quite a lot about the tree.
The differences between the Red and White families are significant and more important than the differences from one species to another within a group.
* The acorns of White Oaks mature in one growing season and germinate in the Fall. Red Oak acorns take two years and germinate in the Spring.
* Deer reportedly prefer eating White Oak acorns; Wood Ducks prefer Red Oak acorns. In Eliza Howell Park, the Blue Jays I watch harvesting acorns spend most of their time in Red Oak trees.
* Red Oaks grow faster than White Oaks; White Oaks grow larger and live longer.
* Both Red Oak and White Oak are hardwoods, with White Oak rated a little higher on the hardness chart.
One way of identifying whether an individual tree is in the Red Oak or the White Oak group is by the bark. White Oak bark has more furrows and ridges than Red Oak.
Here are the same two trees, placed side by side.
Most people, definitely including myself, tell the difference by the leaves. The leaves of White Oaks typically have smooth or rounded edges on the lobes. Red Oak leaves usually have pointy tips at the end of the lobes.
The 8 leaves in the next two collages are from trees that I would identify as White Oaks.
The above can be compared to the leaves of Red Oaks — the next 2 four packs.
Distinguishing between the two types of oaks by leaves is much easier, in my opinion, than by the bark. The simple question is whether the lobes are pointed or more rounded.
On different occasions in the last several years, individuals on nature walks have indicated that they knew that the leaves of one oak group were pointed and that the leaves of the other were not, but that they didn’t remember which is which!
While thinking about a memory aid that I could suggest two years ago at this time of the year, I walked past Halloween decorations in a neighborhood yard, decorations that included a graveyard symbol.
When trying to remember which oak group has pointed leaves, one can think of this Halloween symbol. For tree identification purposes, “R I P” means “Red is pointed. ”
If leaves are present, most oak species can fairly easily be identified as either Red or White. Of course, a general guideline is a just a general guideline. There are exceptions.
Here are two species in Eliza Howell that required that I identify the species first before I could know the group.
“Oak” is a type of tree that most of us hear about early in life and have some basic familiarity with. But, as with so much else that one encounters on repeated nature walks, there is always more to learn and appreciate.
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