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The yellow flowers of bladderwort emerge from the shallow water of a pond. Photo by Larry Weber

Northland Nature...Bladderworts flower and feed in the wetlands of August

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The marvelous month of August continues to unfold. Whether it is bird migrants, spiders, butterflies, dragonflies or a whole host of other insects, these late summer days continue to give us plenty of animal news.

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But what this time reveals goes far beyond these critters. Our gardens are providing much to help fill the tables.

Raspberries and blueberries add juicy desserts. And I look forward to a good crop of blackberries and choke cherries a bit later this month.

The flora of July is still present along the roadsides, but the milkweed, dogbane, evening primrose, fireweed and cow parsnip, though holding layers of flowers, are now past their peak. August, however, comes back with more to see.

A couple of species of sunflowers, goldenrods and asters are now blooming, with more to come.

Among these long-lasting plants that continue until the frost, I see scatterings of other late-season flowers: bergamots and blazing star provide various shades of purple while butterflyweed adds bright orange to roadsides and fields.

With all the water activities that Northlanders enjoy at this time, we can find more flora of the wetlands as well.

Most obvious are the large flowers of yellow pond lilies and the even bigger blossoms of white water lily. Both have flat leaves: oval with the yellow, round on white ones, while flowers reach up above the surface.

But there's more to be seen along the shore. Here are the three white petals of arrowheads. Plants get this name from the shape of the leaves. Light purples of Joe Pye weed and swamp milkweed blend with oranges of jewelweed here too.

As I looked at this aquatic bouquet recently, I noticed a large number of small yellow flowers sticking up from the shallow waters. The florets were mostly round with a lower spur and were growing on a stalk straight up from the water. A little searching revealed the subsurface stems and lacy leaves. The stem was also lined with small bag-like growths. I was looking at a flowering group of bladderworts.

Despite the profuse yellow flowers over the water's surface, often among lily pads, it is the sacs of the underwater stems, often overlooked by the casual observes, that give the plant its name. (The suffix "wort" is fairly common in plant names and should not be confused with "wart" even though they are pronounced the same. Essentially, "wort" just means plant.)

Not only do the sacs provide a name for the plant, they also help to give it needed food.

As a true marvel of nature, these little bags (bladders) serve as traps to catch minute insects and other aquatic life. The prey is sucked into the bladder and held under water. Captured and subdued in this way, the prey is then digested by strong enzymes produced by the plants.

Bladderworts are one of four general groups of insect-eating plants that grow in the region.

Bogs are the home of the tall pitcher plants that use their hollow leaves to entice and digest insects, and here too are the tiny sundew plants that use sticky drops on the little round-shaped leaves to capture insects.

Though the sundew is much smaller than the pitcher plant, its method of capture is more active since the leaves wrap around the prey.

Among the rocky cliffs of Lake Superior's north shore grows butterwort. This plant uses flat sticky leaves (feeling like butter) to hold unsuspecting insects. Leaves then roll over the gathered food.

The Venus flytrap is often thought of when we speak of insect-eating plants. This well-known plant does indeed actively devour bugs, but it lives in the swamps of the southeast, nowhere near the Northland.

Whether it is bladderwort, pitcher plant, sundew or butterwort, all have flowers and green leaves, like "normal plants," but they need extra nutrition, which they get from the abundant insect meals.

All grow in damp places, but it is only the bladderwort, probably the most common of all our insectivorous plants, that feeds in the subsurface of ponds, swamps and lakes.

With the high waters due to the wet spring, I have found many of these plants with their yellow flowers and underwater traps in recent weeks.

Along with other plants of August, I expect to see these yellow flowers rising from the waters for the next several weeks as they flower and feed in the wetlands of late summer.

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