Updated: May 8
written by Yvonne Malone
For a minute, sit back and think about your best teacher ever. A teacher so knowledgeable and enthusiastic about a particular topic that it made you think about things differently and, maybe even want to learn more…
Greener Grove kicked off the new year by welcoming Andrew Hipp, Ph.D., to speak at our January meeting. The topic, “All About Oaks,” is based on his recent book, Oak Origins: From Acorns to Species and the Tree of Life, and his work as Herbarium Director and Senior Scientist in Plant Systematics at The Morton Arboretum.
Dr. Hipp shared his vast knowledge of oaks by describing their fascinating evolutionary tale through millions of years to today. With approximately 425 species of oaks worldwide today, he explained how oaks in one geographic area are connected to those in another by taking us back in time - and describing how wind pollination works.
As each pollen grain makes its journey, weather and wind play a crucial role in determining whether a grain makes it to the female flower. For example, if a heavy rain storm falls just as the male catkins bloom on an oak tree, the pollen they carry may become too wet and clumpy to be carried by the wind to reach a female flower.
If pollination does occur, other factors will influence the number of acorns produced and whether one becomes a seedling. For example, in a mast year (when trees produce a lot of acorns), squirrels and jays will have plenty to eat and the chance an acorn becomes a seedling increases. A fun fact we learned: When we see a squirrel rotating and shaking an acorn in its front paws, it is assessing the acorn’s weight. A more weighty acorn means it contains more nutrients and is less likely to be infested with weevil larvae.
Stepping back from how a single pollen grain can eventually lead to a tree whose life can span decades, even centuries, Dr. Hipp described how the story of oaks is woven through “The Tree of Life”, one that connects all organisms who have inhabited Earth, from oak’s last common ancestor to humans today.
Dr. Hipp concluded his presentation by taking questions, including one about the future of this keystone species. Of the 425 species of oaks worldwide, approximately 31% are at risk of extinction. A sobering fact to be sure.
As we move into spring here in Downers Grove, be sure to clear away any invasive plants like buckthorn and honeysuckle. This makes room for acorns (and other native plants) to emerge and get the nutrients and light they need to grow. You can also volunteer to do the same in DuPage County Forest Preserves. Check out their upcoming Restoration Workdays here. Or consider volunteering in Downers Grove's Lyman Woods or Belmont Prairie through the DG Park District here.
To purchase a copy of Oak Origins: From Acorns to Species and the Tree of Life, visit Anderson’s Bookshop, The Morton Arboretum gift shop, or your local independent bookstore.
