Did you know that there are a handful of wildflowers that are only found in the Great Lakes?
Thanks to a history of Ice Age glaciers and continental sheets, this region’s ecology is able to play host to some special flowers and plants that you won’t find anywhere else.
The Great Lakes’ sandy shores
Before we delve into the species that are unique to the Great Lakes region, we have to take a look at the region as a whole to understand what, exactly, makes this area so unique.
The answer lies buried in the sandy soil on the shores of many of the Great Lakes — particularly on the shores of Lake Michigan.
These bands of sand are scars and remnants of the last Ice Age, which ended roughly 11,700 years ago. During that cold, chilly period of Earth’s history, nearly the entire top half of North America was covered by a massive continental glacier known as the Laurentide Ice Sheet; a 2,000-mile-long blanket of compressed ice and snow measuring nearly a mile thick in places!
This ice sheet traveled south across the continent and gouged deep marks into the ground as it dragged boulders, ice and stones across the soft earth. Eventually, the ice sheet stopped growing and it began to recede, leaving flattened landscapes and deep scars in its wake. It also left piles of dirt and debris at its southernmost edges — just as a bulldozer leaves piles of dirt behind after it is done pushing it around.
The retreating glacier also left behind a lake — a few lakes, actually, and they were pretty great lakes! The water levels in these lakes rose and fell as the Ice Age slowly came to an end, and the erosion from these fluctuating water levels is what created the beaches, marshes, wetlands and sand dunes that are now dotted all over the Great Lakes’ shorelines.
This is why places like the Indiana Dunes National Park can exist in the middle of a continent, miles from any deserts, mountains or coastlines and why the Great Lakes have stunning sandy beaches that rival those of the coasts!
These sandy beaches are also home to specific types of plants that thrive in the soft soil and, since there aren’t many other places like the Great Lakes anywhere nearby, these plants are totally restricted to this unique ecosystem and can’t be found anywhere else in the world.
So thanks to a giant ice sheet weighing a cool 3.8 billion tons per square mile, we now get to enjoy pretty little flowers dotting the shores of Lake Michigan. Cool, huh?
Let’s check them out!
The Great Lakes’ 4 endemic species
Pitcher’s thistle
Cirsium pitcheri
Pitcher’s thistle is a rare, spiny thistle that is found only in the upper Great Lakes region where it grows in sandy or gravelly soils along the shores of lakes and rivers. The dandelion-like flowers are pale and yellowish in color and grow atop leggy stalks covered in blue-green leaves.
These late-summer blooms are a favorite food of the monarch butterfly, which feeds on the nectar to prepare for its annual migration. The thistles are also vital to shoreline erosion prevention, as their roots help stabilize loose soils and sand along Lake Michigan’s coast.
Unfortunately, because of their extremely localized existence and delicate habitat, Pitcher’s thistles are listed as a threatened species on both a state and federal level.
Lake Huron tansy
Tanacetum buronense
Another dandelion-like plant with a marigold-like flower, the Lake Huron tansy is a bright and colorful sight along the Great Lakes’ shores. Clusters of yellow domed flowerheads stretch straight up from long stalks and vibrant green leaves, setting them apart from their more muted thistle cousins.
Dwarf lake iris
Iris lacustris
This small, delicate blue iris is hard to overlook.
Growing in loose, sandy soils along the northern shores of Lakes Huron and Michigan, the dwarf lake iris is a vibrant sight during the late spring and early summer months. The plant itself is made of short, thin stalks, but the bright blue-purple flowers atop them measure almost two inches in length! Three of the six large purple petals display brilliant yellow and white “eyes” that stand out against the deep purple and dark green leaves.
The iris is also, unfortunately, a threatened species at both the state and national level. The delicate flowers thrive on the sandy soils and limestone coastlines of only a small portion of the Great Lakes, and that fragile habitat is under constant threat from chemical spraying, off-roading vehicles, human interference and urban development.
Luckily, though, there are plenty of efforts to increase public awareness of the small but beautiful flower. The dwarf lake iris was listed as the official wildflower of Michigan State in 1998, and there are strict regulations around recreating in areas where the irises are known to grow.
Houghton’s goldenrod
Solidago houghtonii
Houghton’s goldenrod is a small, yellow-flowered goldenrod that is found only in the upper Great Lakes region where it grows in sandy or gravelly soils. The late-summer blooms are small and yellow, though they cluster in large groups above tall, thin stalks. When they grow in large groups, their yellowish-red petals shimmer like gold in the sunlight!
Keep an eye out for these special plants next time you’re out and about among the dunes and sandy shores around our luxury Chicago apartments!
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Featured photo courtesy Pixabay/Thumbwind