Southern Red Oak

Like many other tree species in the New Jersey area, the southern red oak is a deciduous tree, which means that the leaves fall off and regrow seasonally – a common characteristic of trees growing in the temperate zones. Because of this, during the fall months the southern red oak’s leaves will turn red in color and droop off the branch until they ultimately fall off. The simple leaves of a southern red oak are very distinguishable. They grow in an alternate arrangement in the stem and have pinnate leaf venation, which means veins branch off from the central mid-vein in a parallel fashion toward the margin, or edge, of the leaf. The leaves are also lobed, with either 3 or 5 lobes, typically. Lobed leaves are a common feature of oak species. This particular oak has pointed lobes, which is characteristic of the larger group of red oaks, whereas white oaks have rounded leaf lobes – you can find those at Rowan, too. The southern red oak can also be identified by its characteristic dark gray straight trunk with deep grooves in between the bark.

You may be asking yourself, well how does the southern red oak reproduce? Unlike animals, there are many plant species that are monoecious, which means they have male and female reproductive organs present on the same plant. The southern red oak falls in this group of monoecious plants. In the spring, the southern red oak will produce drooping, inconspicuous male flowers called catkins and also female flowers called clusters. Pollination occurs by wind with this species, and this makes self-pollination the default mode of reproduction for southern red oaks, meaning the pollen from a tree’s catkins will travel to and fertilize a female cluster on the same oak tree. However, cross-pollination between two members of the same species can also occur if they are growing in the same area. In some cases, hybrid oaks will also occur when two different oak species undergo fertilization.

The product of reproduction in southern red oaks is an acorn, which contains a seed, but most southern red oaks do not start producing acorns until they are at least 25 years of age, and even still, peak acorn production does not occur until 50-75 years of age. This may seem like a long time, but the southern red oak can actually survive to be nearly 300 years old! Acorns take 2 full years to mature, and they germinate in the spring after the second year of maturation. Acorns also contain very concentrated levels of tannin, which is a substance that is bitter and can be toxic to insects or animals. This keeps herbivorous animals from eating the acorns and destroying the seed inside. With that being said, the southern red oak still acts as a major source of food for many animals including squirrels, black bears, turkeys, and songbirds. Many butterfly species also inhabit the large branching southern red oak.

There are seven other southern red oaks on campus, as well as several other species of oak tree. You can also find other trees in the same family as the oaks, such as sawtooth oak and willow oak. All species of trees play an important role in their ecosystems, and learning about these species can be fun, interactive, and meaningful to your life. I hope you continue to explore Rowan University’s campus and learn more about the vast array of tree species that are all around you!

These resources are a product of Dr. Sara Wright’s Plant Diversity course in the Biological Sciences and Biomedical Department. My name is Luke Castagna, and I will earn my Bachelor of Science degree in Biological Sciences in 2022.. I plan to pursue a career in the humanitarian aid field. You can read more about me and the Southern red oak below.