January 20, 2021
A Tale of Two Maples: Acer saccharum versus Acer platanoides
By Robin Kuehn
Native: Sugar Maple, Acer saccharum
What resident of the northeast United States doesn’t have a soft spot for our iconic sugar maples? With some of the most easily-identifiable leaves in our woods and a habit of growing in the nutrient-rich, damp valleys and slopes across the state, this friendly tree is a familiar backyard staple.
While this tree is beloved for its beauty, its high-value timber and firewood, and as a food source for deer, rodents, and pollinating insects, its crowning achievement is in the production of maple syrup.
According to the New York State Department of Agriculture and Markets, “New York State ranks second in the nation for maple production, producing 820,000 gallons of maple syrup in 2019 that marked a 75-year record. New York is also home to the largest resource of tappable maple trees within the United States and more than 2,000 maple sugar makers.”
Here in Ulster County, tapping trees for syrup begins sometime around mid-February (though the traditional season has been heavily affected by climate change). If you have a maple tree at least ten inches in diameter on your property, plus some tools and a fair amount of patience, you could try your hand at home-made maple syrup!
Standing up to around 70 feet tall, this maple is an indicator of a mature hardwood forest. These trees start producing seeds at 30 years old, which seems like a long time until you learn that some individual trees have been found to be over 500 years old! They are incredibly dependent on forests that have been protected from disturbance by logging, construction, and other human endeavors. Of course, you don’t need to hike to the middle of a park to see them, you can plant one right in your own backyard — if you have the space! It is a much more desirable tree than its chief rival, the Norway maple. For more information on identifying these two species, see below.
Non-Native: Norway Maple, Acer platanoides
Like many other invasive species featured in our Species Spotlights, the Norway maple was introduced to the United States for decorative purposes. This tree of Europe and Western Asia was introduced by John Bartram, a botanist and horticulturist who offered it in his nursery catalog in 1726. It quickly gained popularity and over the years was used in many suburban neighborhoods, especially as a street tree.
From the cities and suburbs where they were widely used to replace the dying American elms, Norway maples readily escaped into wild forests. The attributes that made them easy to grow in urban environments — namely their quick growth and high tolerance of disturbance, air pollution, heat stress, and poor soils — made it easy for them to march across the continent, displacing native trees along the way.
While Norway maple isn’t the only introduced/invasive maple species in our area, it is potentially the most problematic and likely the most widespread. They tend to leaf out earlier in the spring and create denser shade than our native forest species. This is a nuisance for anyone trying to grow plants beneath one, but it is extremely detrimental to early spring wildflowers such as Dutchman’s breeches, mayapple and dog-toothed violets that depend on unimpeded early spring sunlight.
The deep shade beneath the Norway maple also discourages the growth of other tree seedlings and understory shrubs, leading to a less-diverse forest and soil that is highly prone to erosion. Their shallow roots make them susceptible to blowdowns. If that wasn’t enough, it is also preferred as a host tree by the Asian long-horned beetle, known to be one of the country’s most destructive pests to native maples and other hardwoods.
Is this a sugar or a Norway maple?
Perhaps you have some maple trees on your property, and want to know if it’s a lovely native or a pushy invasive? The easiest way to tell these two species apart is by the leaves: Norway maples have 5 to 7 lobes per leaf (if the leaf was a hand, the lobes are the fingers). Sugar maples have up to 5. The notch, or the corner between the lobes, is rounded in Norway maples and a sharper “V” in sugar maples. And if you break the stem of a Norway maple, a milky white sap flows from the greenery, as opposed to the clear sap of a sugar maple.
They are also easily distinguished by their seeds, as the Norway maple has wings that stretch out (similar to moth wings) and the sugar maple seeds have wings that stretch straight down (similar to a cicada).
But hey, isn’t it January!? There are no leaves to identify at the moment, so one must rely on the bark and buds instead. The bark of the sugar maple tends to be rougher and more thickly-furrowed than the Norway maple, but I think buds are the best winter identification tool. If you look at the terminal (end) bud on a branch, the Norway maple is rounded with only a handful of leaf scales visible, while the sugar maple is more pointy and narrow with 4-8 dark-edged scales.
For more information and photos, see the links below. You might also take a photo and submit it on iNaturalist, which is my go-to when I want to be more certain of my flora and fauna identification.
~ Robin Kuehn
Maple Identification Aids:
Love to color? Check out these free maple coloring pages: