An oak is a beautiful, long-lived tree. They don’t erupt in floral fireworks in the spring, but their autumnal display is second to none. They’re planted in parks, back yards, and campuses for their generous shade, farmed for their highly valuable lumber, and climbed by adventurous children and young-at-heart alike. The oak belongs to the noble Fagaceae tree family, along with Beeches, Chestnuts, and Chinkapins. Roughly one year out of every three, an oak tree is capable of producing a huge crop of healthful and delicious nuts that sustained many civilizations throughout human history.
Did you make a confused face when I mentioned oak nuts? Yes, we are talking about acorns!
Acorns are not suitable for fresh snacking like pecans are, but after some simple processing (involving soaking the nuts in water to remove their bitter tannins) they can be ground into a versatile and gluten free flour that can be baked into cakes, cookies, breads, and more. They can also be made into porridges, soups, and beverages. Their culinary use is more similar to grains than the nuts that might more commonly come to mind, although their cultivation requires none of the ecologically destructive tillage practices and deleterious sprays that are commonly employed in grain farming. The extensive root system of the oak tree helps to protect soil from the forces of erosion, which in turn protects clean water. The many leaves of the oak tree filter the air of the carbon that we have too much of, and infuse the air in turn with plenty of the oxygen that we need more of. Since these trees grow all by themselves and produce plentiful acorns in the wild, we know they won’t be high maintenance as crops. This is Earth-positive agriculture at its finest.
Aside from a few fun experiments with acorns, I haven’t really cooked with them in quantity. But that’s all about to change. For me, 2020 is to be the year of the acorn. I bought a new nutcracker so I can process them in bulk, and gathered all the publications I could find on the subject. Over the past month, I’ve been searching for oak trees everywhere I go, and keeping a detailed log of the species, location, and approximate age of each tree that I find, and noting whether or not the tree is producing acorns this year. My hope is to collect a sampling of acorns from every native oak species to experience and compare all the available flavors, and to collect a large quantity of acorns from trees of the easier-to-process white oak group for recipe experimentation and general winter sustenance. I probably won’t realistically gather acorns from every single native oak species this year, but eventually, I aim to collect them all.
Oak Tree Groups
According to Wikipedia, there are around 600 species of oak trees, encompassing a multi-continental native range and spanning multiple oceans. Here in Indiana, we have quite a few native species of oak trees from the white oak group and the red oak group. The white oak group produces the sweetest nuts that ripen about six months after the tree flowers, and these nuts require less processing (soaking in fewer changes of water), since they contain lower levels of bitter tannins. The red oak group produces nuts that are higher in tannins, and ripen about 18 months after the tree flowers. Because of the higher tannin content, acorns from red oak trees require more work to process the bitterness out of them (you soak them in extra changes of water). However, all acorns are edible as long as you process them until they are no longer bitter. We have planted one hundred Swamp White Oak trees in our wetland food forest in anticipation of their delicious acorns, and so far they are thriving more than any other tree species we have planted. We also inherited a beautiful mature Bur Oak tree that grows on a steep slope between our high and low fields, and that tree is loaded with acorns this year. Most trees in the White Oak Group have rounded lobes on their leaves, and most trees in the Red Oak Group have pointed lobes on their leaves. However, this is not a 100% hard and fast rule. If you have space for an oak tree on your land, be sure to select a species that is native to your area. Native trees are usually easier to grow and more beneficial to your local ecosystem. Although you might notice some bite marks on the leaves of your oak tree, or an occasional acorn with a hole in it, please don’t spray as these are not usually a serious problem for the tree, and are a sign that the tree is supporting the vibrant web of life in your community.
Indiana Native Trees of the White Oak Group
- Bur Oak (Quercus macrocarpa). A splendid tree with a very nice form and especially nice acorns. It is a very adaptable tree whose native range includes all of Indiana, and also dips down as far south as Texas and reaches up as far north as Canada.
- Chestnut Oak (Quercus montana). Native to upland regions of eastern and southeastern United States, including the southernmost parts of Indiana.
- Chinkapin Oak (Quercus muehlenbergii). Native to all of Indiana and several neighboring states. Prefers upland soils.
- Dwarf Chinkapin Oak (Quercus prinoides). Native to all of Indiana and several neighboring states. Prefers dry, acidic soils.
- White Oak (Quercus alba). A huge oak tree native to all of Indiana, as well as most of the eastern United States.
- Overcup Oak (Quercus lyrata). A great lowland oak tree native to several southeastern United States, including a very small area of southern Indiana.
- Post Oak (Quercus stellata). Native to southern Indiana and most of the southeastern United States. A smaller oak tree that prefers dry soils.
- Swamp Chestnut Oak (Quercus michauxii). Native to a small section of southern Indiana, and several Southern, Eastern, and Southeastern United States. Very similar to Chestnut Oak, but native to lowland regions instead.
- Swamp White Oak (Quercus bicolor). Native to lowlands across all of Indiana, and a few neighboring states.
Indiana Native Trees of the Red Oak Group
- Black Oak (Quercus velutina). Native to all of Indiana, and to a huge range encompassing much of eastern United States. Adaptable to multiple soil types.
- Blackjack Oak (Quercus marilandica). Native to dry soils of southwestern Indiana, and several southeastern United States.
- Cherrybark Oak (Quercus pagoda). Native to a tiny corner of southwestern Indiana, but mostly to southern states. Thrives in moist bottomland soils and tolerates occasional flooding.
- Northern Pin Oak (Quercus ellipsoidalis). Native to uplands of northern Indiana, northern Illinois, and a few other northern states.
- Pin Oak (Quercus palustris). Native to moist but well-drained soils across all of Indiana, and to our neighboring states to the west, south, and east.
- Red Oak (Quercus rubra). Native to all of Indiana, and a huge range encompassing most of the eastern United States and parts of Canada. Adaptable to multiple soil types.
- Scarlet Oak (Quercus coccinea). Native to splotches of southern, northern, and central Indiana and most of the northeastern United States. Grows best in well-drained, acidic, dry or sandy soils.
- Shingle Oak (Quercus imbricaria). Native to most of Indiana, as well as our neighboring states to the west, east, and south. Adaptable to many soil types.
- Shumard Oak (Quercus shumardii). Native to most of Indiana and to the south. Adaptable to multiple soil types.
One notable “oak” we thankfully do not have in Indiana is “poison oak”! Poison Oak is not related to oak trees at all. Its in the same genus as (closely related to) poison ivy and poison sumac, and its plant family curiously also includes cashews, pistachios, and mangoes! Poison “oak” is named such only because the leaf shape vaguely resembles the shape of an oak leaf. The similarities end there.
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