The Amazing Transformation of Wild Rice

Apr 9, 2019

For this month's Field Notes feature, Susan Knight discusses Wild Rice, and its amazing transformation from spring to fall.

It’s almost spring. You can feel warm air wafting amidst the chill.  The lakes are starting to melt; it will be paddling time soon.  My favorite paddle any time of year is the south basin of Allequash Lake. If you could take a time lapse sequence of yourself paddling on Allequash you would see a remarkable metamorphosis. In the first frames you are paddling on a quiet lake in spring, not unlike many other lakes.  Though it is hard to tell without any underwater plants to betray the current, water is gently flowing over soft mucky sediments – perfect habitat for wild rice – and the star of this story.

You see last year’s cattail stalks with ragged, disheveled hot-dog-shaped seed heads on the firmer, far edges of the water. You hear the first male red-winged blackbirds noisily proclaiming territories in the marshy margins. Off in the distance, some trumpeter swans have returned; they know this water will be rich in submerged and emergent aquatic plants and will be a good place to raise young.  Though unseen, wild rice seeds dropped last fall are starting to germinate in the oxygen-poor but warming soft sediments below.

A few weeks on and the first floating leaves of wild rice are visible on the water surface.  You see pond lily leaves starting to float on the surface and sometimes competing with wild rice for space on the shallow, muck-bottomed water. Black terns have returned, dive bombing interloping paddlers to discourage them from encroaching on their nests. In the next frames you begin to see the first emergent stems of wild rice, beginning to “stand up”.  The floating leaves of wild rice fall away, and the stalks, or culms, grow up out of the water. New cattail stems are emerging on the edge of the water, where there is firmer ground, but the soft sediments and gentle flowing waters are the domain of the wild rice.

Summer is nearly here. Where there had been an expanse of open water, there is now a short, prickly forest of wild rice poking into the air above the water. You can now hear yellowthroats calling out their distinctive “wichety-wichety-wichety” from their perches.  Cool June days give way to warmer summer, and wild rice plants reach their full height, standing several feet above the water surface.  The paddler can no longer see much of the lake; the tall wild rice stalks create a curtain on all sides, and the paddler must work hard to cut a path through the dense stalks.

The transformation is complete as the wild rice plants start to flower.  Each plant has two tiers of flowers; the female flowers top the plant in a tight spike where the seeds will form.  Below the female flowers is a pyramid-shaped panicle of male flowers - a loose arrangement of floppy anthers dangling above the water. Conveniently, the female flowers are fertile before the male flowers on a single plant, guaranteeing that pollen from a neighboring plant, and not from the same plant, will pollinate and fertilize the female flower. Pollination and fertilization is a serious matter for these plants; wild rice is an annual plant and must produce seed for the next year if the plant is to persist in this water.  By late August, the fertilized flowers are now swelling with ripening seeds at the tip of the plant. 

Soon the human and non-human harvesters will descend on this natural buffet. Ducks, such as Blue-winged Teal, Wood Duck, Mallard, Redhead, Canvasback, and other puddle ducks all consume wild rice.  The early arrivals to the lake, the Red-winged blackbird and Common Yellowthroat, also consume rice once it is ripe. Other waterfowl such as geese and swans may also consume the seeds, but these birds often harvest the young plants themselves, mowing down the stalks before they get a chance to produce seed. During the summer, muskrats will use wild rice stalks to construct their lodges. Along with the resident birds, migrant waterfowl will also stop to feast and rest on wild rice on their journey south to their winter quarters.  For at least hundreds of years, humans have harvested wild rice in the upper Great Lakes area. After roasting and threshing, wild rice is a reliable, nutritious, and delicious staple food.  When the rice is ripe, it easily falls into a boat with a slight whack of the harvesters’ sticks.  Happily, both human and waterfowl harvesters are inefficient enough in their harvesting to allow plenty of ripe rice to fall into the lake, to await germination the next spring.

Our time lapse photography session nears completion as wild rice is harvested or seeds itself into the bottom sediments.  The stalks collapse into the water, creating a dense underwater thatch.  The water is smooth and vacant again, and ready for winter.

For Field Notes, this is Susan Knight of UW-Madison’s Trout Lake Station.