Carnivorous Plants

2024 July 14

On June 14, 2024, Sandy went down to Penegor Lake to see how the fishing was[1], and while there spotted these fairly large and ovious blossoms. And at the base of the blossoms, the plant had leaves like these:

This is probably the most distinctive leaf shape of anything that lives in the Upper Peninsula. These are Pitcher Plants, Sarracenia_purpurea, and are probably the second best-known type of carnivorous plant (with the best-known being Venus Flytraps, but those don’t grow this far north). The pitcher-shaped leaves of the pitcher plant contain a mixture of rainwater and digestive fluids, and when insects fall into them and drown, the plant digests them for their nitrogen and phosporus content. They do this because they grow in bogs that are seriously nutrient-deficient[2], and so they get these critical nutrients from animals that come in from places where these nutrients are available.

Along with the large, obvious pitcher plants, there is another species of carnivorous plant that grows up here. They are the sundews, the little pinkish/purple discs with hairs sticking out that you can see in the bottom left of this picture.

Sundews catch their insect prey differently than pitcher plants do. Each of the hairs on those round leaves has a drop of sticky digestive juices on the tip.

When an insect lands on one of these leaves, it gets stuck in the liquid drop. To keep it from getting away, the hair then bends down so that other hairs can stick to the insect, until it is all glued down and immobilized, ready to be digested.

The sundews can grow in fairly extensive colonies, making a broad, shimmering, purple mat across the bog.

The Michigan State University Extension Service says it is most likely Drosera_anglica, or English Sundew. In spite of the name, they don’t appear to be from England particularly. They are a cold-weather species that runs around the arctic circle, and it looks like we are in the southern part of their range.

In general, carnivorous plants tend to be more tropical species, we only have these few species that live this far north. If you want to have an idea of what is available, check out the carnivorous plant nursery.

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[1] The Michigan DNR recently stocked that lake with grayling in an attempt to re-establish them in the state. Arctic Grayling used to be very common fish in Michigan, but they need cool water and shade, and when the state was largely logged off in the late 1800s/early 1900s, the rivers and ponds they had lived in lost their shade and warmed up. Now the trees have largely grown back, and so it is reasonable to think that the grayling can be re-established.

[2] The type of bog they live in are the ones that are essentially big potholes that fill with rainwater and snowmelt. They aren’t fed by groundwater or surface streams, and so there is nothing to carry in nitrogen and phosphorus, and also nothing to neutralize acids from decomposing plant matter. So these bogs end up filling with nutrient-poor, acidic water that most plants can’t deal with. This is a very distinctive environment, and has a completely different set of plants growing in it than we get in “fens”. A fen is superficially similar, but it has water coming in from small streams or underground springs, and so they have significantly higher nutrient levels.

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