Of skunk cabbages and other skunk cabbages

Every year I forget: early spring is a prolonged time in this part of the world. The time between the first shoots and anything actually flowering is measured in weeks, not days; and it can be a month to six weeks until there are leaves on trees. On a walk in the UW Arboretum in early April, you can sense a great many things beginning to stir, but still in the form of a few green leaves poking up. I didn’t even see any bloodroot, which is a pretty reliable early wildflower there.

In the marshy ground verging on Lake Wingra, though, something was doing more than just tentatively throwing up some shoots: there was a profusion of Eastern skunk-cabbage (Symplocarpus foetidus):
Skunk cabbage (Symplocarpus foetidus), UW Arboretum
At this point of the season, when nights below freezing are more frequent than otherwise, they have a distinct advantage over competitors, because, as it turns out, they thermoregulate; and not through some “trapping warm air” dodge either – no, their mitochondria burn oxygen and make heat, just like mammals. In fact:

The spadix of Symplocarpus foetidus L. maintains an internal temperature 15 degrees to 35 degrees C above ambient air temperatures of -15 degrees to +15 degrees C. For at least 14 days it consumes oxygen at a rate comparable to that of homeothermic animals of equivalent size.

(From abstract of “Heat production and temperature regulation in Eastern skunk cabbage”, Roger Knutson in Science, 1974. Link is to abstract only; full text is behind a paywall.) This helps them come out of the ground earlier than competitors, and, as an added bonus, helps disperse their stench more effectively.

Though to be honest I’ve never found the smell that bad – just sort of earthy and marshy. When I’m in wetlands I expect to smell a certain amount of decay: it’s part of the charm. Western skunk-cabbage (Lysichiton americanus – a completely different genus) on the other hand… during my brief spell in Redmond, Washington, there was a swampy plot near my apartment building that always thronged with Western skunk-cabbage in early spring, and man did that reek. And that despite not even having the heat-generation trick. Maybe it’s just more noticeable because I didn’t grow up around it? Anyway, I would have sworn I had any number of pictures of Western skunk-cabbage, but apparently I didn’t keep any of them.

One thing in common between here and there: if there’s skunk-cabbage, horsetails can’t be far behind.


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