Willow Oak

While we are not sure of the exact age of this tree, we do know that this is a mature tree. This means that the tree is old enough for reproduction. Willow oaks become mature and start producing reproductive structures after 15-20 years of age. The willow oak is a member of a much larger group of trees called angiosperms, which are plants that produce flowers and bear their seeds in fruits. This is how the tree reproduces. Willow oaks are monoecious, meaning they contain both the male and female reproductive structures on the same tree. The male flowers, also known as catkins, are yellow and grow in droopy clusters that begin to bloom in late spring. This same type of inflorescence, or flower cluster, can be found on other oaks throughout the campus.

Flowers are essential to an angiosperm’s reproduction. The flowers contain a few very important parts. The long protrusion in the middle of a female flower is called the pistil. At the base of the pistil, you can find the ovary and the ovule. Male flowers have stamens, instead. At the ends of the stamen, you will find pollen. The pollen can travel from the stamens to the pistil on a female flower with help from wind in this species. Because this species is wind-pollinated, you might not even notice the flowers. They are not trying to attract animals in this case! Wind-dispersed pollen will fertilize the egg cell inside of the mature ovule of a female flower, creating a zygote that develops into an embryo contained inside a seed. Seeds are further contained inside fruits, and for this species, the fruit is an acorn. It’s pretty impressive that a single acorn can make an entire oak tree – they’re not just food for squirrels! The best quality acorns are picked straight from the tree, and they should be collected when the color is a saw dust or sand color.

The willow oak is a hardy tree and known to live for a long time. However, like other plants, it is still prone to disease and herbivory. Some possible diseases that oaks are prone to are shoestring root rot, oak wilt, cankers, leaf spots, powdery mildew, and chlorosis. Some pests that love willow oaks are scale, leaf miners, lace bugs, caterpillars, and nut weevils. Squirrels also love to eat the oak’s acorns, which could hinder its reproductive success. However, squirrels might also forget the acorns, and by doing so, they serve as little gardeners who are helping to plant new trees.

Thank you for taking the time to learn about this beautiful willow oak! There are other closely related species at Rowan that I hope you will explore, including other oak or chestnut trees. The Glassboro campus features sawtooth oaks, southern red oaks, white oaks, pin oaks, northern red oaks, scarlet oaks, horse chestnuts, and oak chestnuts, to name a few. I encourage you to continue learning,as we are so excited to share information about these members of our campus community with you!

These resources are a product of Dr. Sara Wright’s Plant Diversity course in the Biological and Biomedical Sciences Department. My name is Valerie Vischoric, and I will earn my Bachelor of Science degree in Biological Sciences in 2023. I plan to pursue a career in nursing. You can read more about me and the willow oak below.