Posted by Angie Hong | Posted in Outdoor Adventures | Posted on 15-05-2014
Tags: ephemeral wetlands, wildflowers
In search of spring this Mother’s Day weekend, we headed north on Hwy 95 to William O’Brien State Park. I had hoped to canoe on the St. Croix River this Memorial Day weekend, but after seeing the river swollen, brown, and flowing fast, I decided I would have to wait until later in the summer. Further back from the river along the trail, we found delicate spring wildflowers scattered throughout the woods like charms from a broken bracelet.
William O’Brien, which was designated as a Minnesota State Park in 1947, protects a number of unique natural habitats, including floodplain forest and groundwater seepage swamps. When the St. Croix runs high after the spring snow melt and heavy rains, the river floods up over its banks, scouring the surface of the floodplain and depositing silt and sediment when it subsides. Tall trees with shallow but far-reaching roots like cottonwood, silver maple, box elder and black willow are specially adapted for the frequent flooding. Further inland from the river, groundwater seeps keep the soil moist year-round. In the spring, an abundance of water burbles to the surface, creating temporary streams and wetlands. Marsh marigolds are blooming right now, cheery yellow flowers with deep green leaves, and clumps of skunk cabbage dot the woods as well. The water in the springs is clear and cold.
On higher ground, woodland wildflowers are also blooming. While hiking, we saw round-lobed hepatica, bloodroot and wood violets. Some of the woodland flowers are ephemeral, meaning they only appear in the early spring when trees and shrubs are still bare and sunlight is able to reach the forest floor. Within a period of less than two months, they emerge, bloom, are pollinated by insects, set seed and then return to a state of dormancy, hidden underground for the rest of the year. Bloodroot, named for its distinctive red sap, flowers for only a day or two before dying. Other woodland plants, like violets, remain green throughout the growing season, though they only bloom in the spring. Some, like hepatica and false rue anemone have colorful sepals instead of petals, which helps to explain their delicate appearance.
In the ponds the frogs are calling. Like spring wildflowers, many of them have also adapted to make use of meadows and woodlands that are only wet in the spring. Approximately half of all frogs and one-third of all salamander species in North America rely on ephemeral wetlands where they can lay their eggs there, safe from hungry fish. Insects like dragonflies and damselflies also lay their eggs in seasonal ponds for the same reason. Further up the food chain, migratory birds and waterfowl follow the St. Croix River corridor on their journey north, stopping over in wetlands along the way.
Spring has finally arrived in Minnesota. Before long, summer will follow fast on its heels in a sweaty jumble of camping and bonfires, county fairs and grubby bare feet. For now, there is the fleeting joy of hiking without mosquitoes and finding flowers in the woods.