Iowa has been blessed with several species of native maple trees, and hosts several more introduced, ornamental maples from different parts of the world. The oak family is divided into two large groups, the white oak group and the red oak group, based on similarities mostly in their leaf structure. Native maples also have two groups, the hard maples and soft maples, but the primary differences are not so much leaf structure. Hard maples are comparatively slow growing upland trees with hard wood that is popular for furniture, cabinets and wood trim. It is from them that maple syrup is made, as well. Soft maples are much faster growing with softer wood. They’re more likely to be found on flood plains. Their sap can make syrup, too, but it takes about three times as much.
The local hard maple is the black maple. It’s a large, gorgeous tree with a well shaped crown made of primarily three-lobed dark green leaves that tend to droop at the edges. It grows pretty much statewide and likes to grow on north and east facing slopes, where it often associates with basswood and maybe some red oaks. It’s a popular yard tree, but creates such deep shade that it can be tough to grow grass under one. Fall color ranges from yellow to orange. The sugar maple is Iowa’s other hard maple, and is a very close cousin to the black maple. It’s native to eastern Iowa, but doesn’t typically grow this far west. It has been planted as a yard tree in much of Iowa, though. Its leaves are primarily five-lobed and don’t droop at the edges. Fall color ranges from yellow-orange to red-orange. Hard maples are shade-tolerant and their seedlings can thrive in the filtered light under shade intolerant oaks and hickories that once dominated our upland forests. Little oaks can’t grow in shade and many of our older oak-hickory forests have an understory of young hard maple saplings, just waiting for the older oaks to age out and die. Our remaining forests could become quite different places without the oaks and their acorns that so much of our native wildlife depends upon.
The most common soft maple in Iowa in the silver maple. It’s a fast-growing floodplain tree with leaves that have a whitish underside; thus giving it the silver name as they flash in the breeze. They can grow to a huge size, with trunks five feet and more in diameter. The wood is weak and prone to storm damage. They’re not a wise choice to plant next to the house. The shade they’ll produce pretty quickly may not be worth the damage caused when one of the limbs comes crashing down on the roof. The red maple’s red blossoms and seeds in the spring and red leaves in the fall give it its name. A few grow native in northeast Iowa, but it is happier farther east. Although it can be a beautiful tree, it often performs poorly when planted here. The last native soft maple isn’t even called a maple, at least not here. Up north it’s called the Canada maple, but here it’s known as box elder. It, too, is a fast growing floodplain tree with a three-parted compound leaf that doesn’t look much like a maple. The box elder is the black sheep of the maple family. Almost nobody cares for it today, but it was widely planted in the early days due to its hardiness and rapid growth. Many a farm grove has gnarled old, hollow box elders, just barely hanging on to life. The tendency to develop hollows relatively early in their life is what makes them important, though. Box elders, along with basswoods, are the apartment houses of the woods and offer den sites for a wide range of woodland wildlife, including raccoon, opossums, squirrels, mice, gray foxes, bats and doubtlessly many more species of animals and birds.
The Norway maple, a tree native to Europe, has been widely planted. It looks like a very dark-leafed hard maple. Break a Norway maple leaf stem and a white, milky sap oozes out. No syrup is made from them. The leaves stay green until fall, and then just fall off with little or no color change. Several varieties of oriental maples in the from of small trees or large shrubs are also planted as ornamentals. The Amur maple, though beautiful, can become invasive as its winged seeds fly away and grow readily. A hybridized tree known as the autumn blaze maple with silver and red maple parents has been widely planted in the last 30 years. It has beautiful red fall color and grows quickly. Many have poor branch structure, though, and may be prone to storm damage as they mature. If you have one in your yard like I do, you should keep an eye on it.
Steve Lekwa is a former director of Story County Conservation.