Michigan Maples

Seven native species and one commonly escaped species of maple occur in Michigan. Maples have opposite leaves. Trees in Michigan with opposite leaves are Maples, Ashes, Dogwood, Horse-chestnut, and Ohio Buckeye. I remember “MAD Horse” to know the opposite leaved trees.

Alternate Opposite
Identifying Terms
Ash fraxinus
Ash

Horse-chestnut and Ohio Buckeye have palmately compound leaves (the leaflets radiate from a single point similarly to your fingers on your palm). Dogwoods have simple leaves with entire margins (no teeth along the edges of the leaves). Ashes are pinnately compound with 7 to 13 leaflets. Box-elder is our only maple with compound leaves and it rarely has more than 5 leaflets. Once you know you have a maple this is how you identify the maples to species:

Cornus florida
Flowering Dogwood
Aesculus glabra
Ohio Buckeye L Horse-chestnut R

Box-elder or Ash-leaved Maple or Manitoba Maple (Acer negundo) has compound leaves, course teeth on the leaflets, and a whitish bloom on the twig. Clusters of paired seeds hang on the tree in the summer and fall giving another method to distinguish this from the ashes.

 Acer negundo
Box-elder
 Acer negundo
Box-elder leaf variations

Silver, Red, Mountain and Striped Maples all have the main leaf sinuses acutely angled at the base. The other simple leaved species have leaf sinuses that are rounded. This takes a little practice to discern but the photos should help.

Acer rubrum
Red Maple L Silver Maple R
Acer saccharinum
Silver Maple L

Silver Maple (Acer saccharinum) leaves are whitish-silver beneath with coarse toothed leaf margins. It has five main lobes with the edges of the middle lobe diverging. It is coarser toothed than the Red and Mountain Maples and lacks teeth in the sinuses. The sinuses extend 2/3 of the way to the midrib. It is one of our earliest flowering trees: flowering before the leaves develop. Silver Maple flowers lack sepals and petals and have a hairy ovary. Chew a twig if you are not sure it is Silver Maple. To me they have a foul taste.

Acer saccharinum
Silver Maple
Acer rubrum
Red Maple
Acer rubrum
Red Maple

Red Maple (Acer rubrum) leaves are whitish-silver beneath with finely toothed leaf margins. It has three main leaf lobes with the edges of the middle lobe converging. The sinuses extend 1/2 way to the midrib and are finely toothed. The first-year twigs are normally red. It flowers when Silver Maple flowers, also before the leaves develop. Red Maple flowers have sepals and petals and a smooth ovary.

Acer spicatum
Mountain Maple
Acer spicatum
Mountain Maple

Mountain Maple (Acer spicatum) leaves are covered with whitish downy hairs beneath. It is a small tree more common in northern Michigan but I know one Oakland Co. stand. Its leaves resemble Red Maple but are more finely toothed and not as deeply lobed. It flowers in the early summer when its leaves are fully developed. The upright racemes of flowers or fruits help to identify this maple.

Acer pensylvanicum
Striped Maple
Acer pensylvanicum
Striped Maple

Striped Maple or Goosefoot Maple or Moosewood (Acer pensylvanicum) is similar to Mountain Maple. Striped Maple has finer, doubly serrate  leaves, lacking hairs on the lower surface. Doubly serrate means that the teeth have smaller teeth. The lobes have tapering tips. Second year twigs have distinctive white stripes. It flowers in the early summer when its leaves are fully developed. The drooping racemes of flowers or fruits help to identify this maple.

Norway, Sugar, and Black Maples all have leaf sinuses that are rounded at their base.

Acer platanoide
Norway Maple
Acer platanoide
Norway Maple
Acer platanoide
Norway Maple

Norway Maple (Acer platanoides) is native to Europe but is now spreading from cultivation into wild areas in southern Michigan. Dark-green leaves with narrow almost awl-like tips distinguish this from Sugar Maple. Leaves are paler underneath than above with hairy tufts in the leaf axils. In the summer its petiole emits a sticky, milky juice when broken. Fruits are paired samaras that diverge 170 degrees. The seeds are flat, barely thicker than the wings. Terminal buds are rounded not sharp as in Sugar Maple. Norway Maple leaves stay green later in the season than Sugar Maples.

Acer saccharum
Sugar Maple
Acer saccharum
Sugar Maple

Sugar Maple or Hard Maple (Acer saccharum) is similar to Norway Maple but with lighter green, five-lobed leaves. Its leaves are more or less smooth underneath but sometimes it has hairs at the leaf base where the veins join. In the summer its petiole emits a non-milky, clear juice when broken. I often look for the sharp terminal bud to distinguish Sugar from Norway Maple.

Acer nigrum
Black Maple
Acer nigrum
Black Maple

Black Maple (Acer nigrum) is a pragmatic species that intergrades into Sugar Maple. Barnes and Wagner in their Michigan Trees accept this species, Voss in his Michigan Flora treats it as a variety of the Sugar Maple, and Reznicek on the Michigan Flora website accepts it with reservations. The extreme forms are distinct.  Black Maple has three-lobed leaves with drooping leaf tips. They are pubescent underneath and on the petioles. Leaf stipules are normally present. Twigs are straw-colored. Black Maple is a tree of wet soil growing in river bottoms. However, intermediates exist that resemble Sugar Maple but with pubescent veins. They could be hybrids between Black and Sugar. It might be better to treat them as one variable species. I’m content to know that I cannot name every individual and call them Sugar / Black Maple.

Here is a link to my blog post on identifying maples using their seeds.

The Michigan Flora Website has further information and more photographs.

There is a citizen scientist project headed up by Steve Gougherty. Steve is a graduate student at the Finzi Lab at Boston University. He is studying Red Maples and needs volunteers to collect samples for him. He started the TASpeR (Traits Across Species’ Ranges) website. This site provides information on his study and a link to sign up if you want to participate. He asks for two collections: one of green leaves and one after the leaves have fallen. He is studying foliar nutrient resorption. His website explains what this means. Sign up if you want to collect for him.

 
Copyright 2019 by Donald Drife

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Soft Maple Flowers

Acer rubrum flowers

Red Maple male flowers

Many people are surprised to learn that trees have flowers. They apparently have not thought through how seeds can develop if there are no flowers. I have been interested in tree flowers since I was given a copy of Norman Fassett’s Spring Flora of Wisconsin when I was a boy. It is a handy little guide to plants that flower in Wisconsin before June 15th and useful throughout Michigan. From it I learned that Red Maple (Acer rubrum) flowers have petals and Silver Maple (A. saccharinum) flowers do not. I began to look for tree flowers.

Acer rubrum perfect flowers

Red Maple perfect flowers

There are additional characters used to distinguish flowers of the two species. Red Maples have separate  sepals and on Silver Maples they are connected. The ovary on Red Maples is hairless and on Silver Maples it is hairy. The soft maples flower before their leaves develop and often I find flowers on the forest floor so it is nice to be able to identify the trees from only their blossoms.

Acer saccharinum flowers

Silver Maple L – male flowers R – perfect flowers

Soft Maples normally have separate male and female flowers. They can be on the same tree. Perfect flowers are known but are rare.

Get out and look at the maples while they are flowering. Watch what is pollinating them. Enjoy one of the first flowers of the year.

Copyright 2016 by Donald Drife

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Maple Spinners

Maple Seeds

Maple Seeds Photo by Robert Muller

Recently a friend remarked, “There are not many spinners this year.” I was puzzled until I realized my friend was talking about maple seeds. When I was a kid we called them propellers or helicopters. I took an informal Facebook poll asking what people called them and they added “Whirligigs” or “Whirligiggers” and appropriately “pain in the butt”.  Technically, it is a samara that is defined as “a winged fruit that does not split open.” Elms, Maples, and Ashes have samaras.

Michigan has six native species of Maples (seven if you recognize Black Maple as distinct from Sugar Maple). The non-native Norway Maple (Acer platanoides) is a too common escaped species.

Silver Maple

Silver Maple

Silver Maples (A.sarrharinum) and Red Maples (A. rubrum) have the best spinners. Silver Maple samaras are 3-6cm (1 ¼ to 2 ½ inch) long and the pair forms a widely diverging angle although often only one seed fully develops.

Red Maple

Red Maple

Red Maple samaras are smaller 1-2.5cm (1/2 to 1 inch) long and the pair is more V-shaped. Often they are reddish. Sugar Maple (A. saccharum) pairs are U-shaped with the samara almost parallel to each other.

Boxelder

Boxelder L- dried seeds in winter R-fresh seeds

Boxelder (A. negundo) has V-shaped pairs and will sometimes hang on the tree all winter. Norway Maples have samara pairs widely spaced so the pairs are almost straight across.

Striped Maple

Striped Maple or Moosewood

Mountain Maple (A. spicatum) and Striped Maple also called Moosewood (A. pensylvanicum) have seeds in branched clusters called racemes. Mountain Maple has seeds approximately 1cm (3/8 inch) long. In Striped Maple the seeds are 2cm (3/4 inch) long. I seldom need to identify maples solely from their seeds. All of these species have other useful characteristics to help determine their identity.

Thanks to Robert Muller for the use of his photo showing the seed of the four species.
Copyright 2015 by Donald Drife

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