July 25, 2010
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I spotted this small plant for the first time earlier this week on a gently sloped, sopping wet and grassy stretch of land next to a lake. The deep purple flower reminded me of a tiny violet. The most striking feature, however, was the whorl of leaves at the base. They were an unusual shade of pale green unlike any other foliage I’d seen up here to date. Sadly, it was overcast and rainy, so photographs were not an option that day; I put it on my mental list of Things To Take A Picture Of At Some Point.
A few days later, as I was stalking bees and wasps amongst dwarf willows and thick patches of vetch near the Coppermine River, I stumbled on a patch of about a dozen individuals of the same purple-flowered plant. And just my luck: the weather was just fine for taking a few pics before I carried on with my hym hunt. I got down on my belly and started snapping away.
I’m not sure what it was that made me pause for a moment to reach out with one finger in order to touch one of the curled leaves; I think that bizarre chartreuse colour was what pulled me in. When I withdrew my hand, I immediately realized something unusual was going on. It was a warm, sunny, breezy day, yet my finger felt wet. I touched my thumb to the finger, rubbing…no, not wet: slimy. Slimy? I touched another leaf, running my finger down its length. Yep, definitely slimy. I inched forward on my elbows until my nose was nearly touching the stem. That’s when I noticed the little black flecks dotting each leaf: flies! Tiny flies! I scanned the other plants and found the same thing. It finally dawned on me: these dainty purple beauties were in fact killer carnivores!
The unusual leaves, and even the stem of this plant (whose name I later learned is Pinguicula vulgaris – common butterwort) are covered with pedundular glands: hair-like stalk cells topped with a number of secretory cells. The secretory cells produce a droplet of mucilage – the slime. When a fly or other small insect touches the ensnaring slime and begins to struggle, the glands produce even more mucous; it doesn’t take long for the prey to become immobilized. Sessile glands on the flat leaf surface then releases digestive enzymes. Nutrients from the prey are absorbed through pores until all that remains is the chitinous exoskeleton. The flowers on butterworts are held high from the leaves on a long stem, so as to avoid killing potential pollinators.
All the insects on the photo above were dead except for the tiny wasp on the stem; I watched it struggle valiantly downwards, its actions becoming increasingly laboured. It must not have known that leaves were just as treacherous, and would in fact mean its death.