The Drooling Sundew

Contrary to the opinion of random passersby who want to come by at all hours “to look at the plants,” the Triffid Ranch isn’t a full-time operation. Oh, it’s a full-time operation, but it’s not the only jobs we hold. Especially during the winter, when all of the temperate carnivores are dormant and the tropical carnivores are resting, having a standard day job like everyone else is a necessity. Among other things, the day job provides health insurance, a steady background income, and a surplus of scintillant conversation from my co-workers. And no, I’m not exaggerating, because I work with a crew of truly unique talents, and we literally have no idea how much our mutual experiences can benefit the other. Ask the engineers circling the coffee machine about their weekends, and the responses sound more like plotlines to a remake of 2001: A Space Odyssey than anything else.

Anyway, compared to the professional musicians, semi-pro glassworkers, and enthusiastic amateur knifesmiths on board, my passion for carnivorous plants marks me as one of the Quiet Ones, and not the oddball in the back corner of the office who isn’t trying to drink himself to death every night. (And yes, I’ve worked in that sort of office. Remind me to tell you about my days working at Sprint one time.) Every once in a great while, though, I can fend for myself, and sometimes even bring something to the lunch discussions that leads to a good bout of Head Explodey.

By way of example, I recently brought a Cape sundew (Drosera capensis) to its current space in my cubicle, mostly because it was a needed touch of green next to a window full of brown. No, let’s be honest: BROWN. Even before the current freezing nights hit, everything was a uniform blasted tan out the office window from the drought, and it was about as pathetic and depressing as a Firefly marathon on SyFy. Indoors, under a good stout 23-watt compact fluorescent bulb in a desk lamp, that sundew promptly perked up and started throwing off new leaves, and I fully expect for it to demand full rights from the UN by spring.

That little sprig of green got more than a few questions from co-workers and project managers, and the first question was “When are you going to feed it?” Since I knew that they’d be less than thrilled by my bringing in a tube of wingless fruit flies, I decided to demonstrate the one commonality between carnivorous plant and human: an appreciation for chocolate.

In his classic volume Insectivorous Plants, Charles Darwin understandably went a little crazy in his enthusiasm over Drosera of all sorts. This book details most of his experiments in understanding sundew mechanics and responses, and he discovered that sundews respond to two different stimuli in different ways. Firstly, the long sticky hairs (officially called “tentacles”) were sensory hairs in that they picked up the movement of prey caught in their glue, and consistent movement of one tentacle caused others in its vicinity to converge on the area, further trapping that prey. Secondly, specialized glands at the tip of each tentacle could ascertain the relative nitrogen content of the item trapped. If the stimulus was something relatively non-nitrogenous, such as a grass stem rubbing against the sundew’s leaf, the tentacles might respond, but the plant wouldn’t try to digest the intrusion. If the stimulus was high in available nitrogen but unmoving, such as a dead bug landing on the leaf, the tentacles wouldn’t respond right away, but they’d ultimately detect the morsel and move to claim it. And chocolate? It’s sufficiently nitrogenous that a sundew might mistake small pieces for gnats or other tiny insects, but without rotting or growing mold while digestion took place.

One of the reasons why D. capensis is perfect for this demonstration is that it’s one sundew that’s singularly enthusiastic in its feeding response. It doesn’t close on prey as quickly as some Drosera species, but its entire trapping surface wraps around prey, sometimes completely surrounding it. Even better, D. capensis‘s output of digestive enzymes is not just visible to the naked eye, but it’s voluminous. Put a mosquito on a Cape sundew leaf, and you get more puddling drool than a doorbell in the Pavlov house.

Anyway, since one of my favorite co-workers asked to see sundew trapping behavior, I pulled some leftover dark chocolate Halloween candy from the department stash (since it’s in a Halloween cardboard display, it’s referred to as “the candy coffin”), scraped off some crumbs, and sprinkled them on the sundew’s leaves. She was a bit disappointed by the immediate response, as she expected something more energetic. “Patience,” I said, “you have to give it some time. If that chocolate was moving, we’d see much faster movement, but it’s still not something you can see in a few seconds.” We left it alone and continued through the day, checking back every once in a while to verify the chocolate’s status.

This morning, my friend came in shortly after I did, and immediately visited the sundew. That’s when she viewed this.

Drooling Cape sundew (Drosera capensis)

Another reason why Cape sundews are great subjects to demonstrate active trapping behavior is that they’re extremely active compared to many other good beginner’s sundews. Note the several folded leaves, where the trapping surface actually folded in half to surround the chocolate. Even better, notice the one on the right that’s curled like a fern fiddleback? That one caught a chocolate crumb near its tip, and the shine down the leaf is digestive fluid. Yes, like most people, Cape sundews drool like fiends when given chocolate.

And now the obligatory disclaimer: I do NOT advocate feeding Cape sundews chocolate on a regular basis, and I definitely don’t recommend it at all for most sundew species. Don’t even think of doing it for most other carnivores. More importantly, as with people, the best results with sundews come from reasonably fresh dark chocolate, so spare the poor plant that dried-up Hershey’s bar that’s been in your desk since 1998. Absolutely importantly, keep the feeding to crumbs: your plant and your co-workers will hate you if you drop a whole Godiva’s truffle in the sundew’s container. As for everything else, anyone have any high school-age kids who want a science fair experiment on sundew sensitivity to different varieties and brands of chocolate?

About these ads

Comments are closed.