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Archive for the ‘plants’ Category

goldenrod galls

Photo by Collin Purrington - http://www.flickr.com/photos/cpurrin1/

It’s March in Vermont, and I sit here typing, snow falls outside. After a few balmy days of rapidly shrinking snowbanks and rising creeks, the prediction for today is 3-6″ of new snow. It makes me wonder about the turkey vultures, the robins, the redwing blackbirds, the green tips of daffodils poking up, even about the moth I saw on the wing last night and the hundreds of spiders crowding the winter-flattened grass near the old pond. That was yesterday, when it was spring. Today it is winter again. But not to worry, it is a fleeting renewal, the last-ditch clutch of a season passing. Summer will come. I think the birds, the spiders, and the moth all know this… and so do the Vermonters, although the weather still galls them.

Some months ago, when the temperatures dipped below freezing, but before layers and layers of snow began their assault on the landscape, I went out and found a couple of patches of goldenrod (Solidago species) and collected a few of the many galls on the stems of the plants. Being a curious person, I noted that the galls showed no sign of anything having exited them, and thought that maybe, just maybe, if I kept them inside and warm for a bit, whatever was due to come out in the spring might make an early appearance for me. I assumed that living inside that hardened gall was a small insect larvae that in the spring would emerge as an adult insect. Well, OK, to be honest I remembered cutting a few open as a kid and finding just such a larvae –  a small, grub-like critter. But I had no idea what the adult version was.

Now, patience may be a virtue and all, but we do have this thing called the internet. It wasn’t long before I knew exactly what to expect coming out of the gall… a goldenrod gall fly (Eurosta solidaginis). This classroom-oriented site by Doug Collicutt was excellent, and this site also had some great photos — most of what I share here comes from these two sites. But before we get into the details, let me finish my particular story.

I set the gall in a mason jar with some screening over the top, and left it alone near a heater. I didn’t keep track of how long it took, but it seems like it was two weeks or so before I walked by it one morning and noted something clinging to the screen on top. A little fly with brown, spotted wings.  I hadn’t really thought that the experiment would work, but there in front of me was a goldenrod gall fly. He wasn’t much to look at really – a little, hunched fly that didn’t seem to move around or fly very well. But still, when you consider that as a larvae he was designed to survive a long winter of sub-zero temperatures in a little brown gall, I was still pretty impressed.

click on any of these for some other photos:

I suppose, when you think about it, any life is amazing. It is a beautiful, mysterious world out there, and our own existence is a marvel in itself. But still, there are moments like this that help one to appreciate the complexity and ingenuity of the world.

Think about it. In the spring, just as the sun is pushing the winter’s snow back and tender new shoots of goldenrods are reaching up into the sun, a little brown fly emerges from a dead, brown gall among last year’s stems. It can barely fly, but it wanders around the goldenrod patch on foot, looking for a mate. It has about 2 weeks to live. If it is a male (like the one in my pictures), its entire mission for its adult life is to find a female and mate with her. He doesn’t eat anything as an adult. He mates and dies, and that is it.

If the fly is a female, once she has mated she finds a growing goldenrod, and using her ovipositor, slips an egg through the skin and into the interior of the plant’s stem. I imagine she deposits a few eggs like this. She, too, does not eat. She simply mates, lays the eggs, and dies.

And the magic begins. Egg hatches to larva. The larva begins eating. The plant senses it, and responds by trying to grow new tissue around it and isolate it. Perhaps the larva secretes a chemical that influences the plant’s behavior, but in either case, the plant fails at its attempt to get rid of the parasite. The little larva gets bigger, and the stem of the goldenrod swells around it, forming a gall. Over the summer, the larva eats and eats, stealing from the goldenrod but not killing it. It spends the summer happily in its gall.

There are threats, of course. Anything that kills the parent plant leaves the little larva without its free lunch. There is no emerging early or crawling over to another plant – its whole life depends on the plant it is parasitizing. There are predators, too. Chickadees know what is in the gall if they can get in. Downy woodpeckers definitely have the means to penetrate the gall. One species of beetle (Mordellistena unicolor) is known to burrow into galls to eat the fly larva, and two species of wasps (Eurotyma gigantea and Eurotyma obtusiventris) use ovipositors of their own to deposit an egg inside the gall. When the wasp egg hatches, it eats the fly larva. And of course there is the curious naturalist who sticks galls in mason jars…

In the fall, as the goldenrod becomes senescent, something triggers the larva to dig itself a tunnel out to the edge of the gall, where it stops just at the skin, and retreats back to the middle. As the goldenrod dies, its tissues become hard, and the larva that misses this step would surely be trapped in the middle of an impenetrable wall of gall. And winter comes.

The goldenrod gall fly larva is one of several species of insects that are able to, as the temperatures drop, produce a sort of antifreeze in their bodies that allows them to survive sub-freezing (and sub-zero) temperatures without tissue damage. It is amazing when you think about it. Anything else would succumb to exploded cell walls and massive damage, but not this little larva. Snow falls, perhaps the dead goldenrod topples and the gall is buried in snow. Maybe it stands through the winter, swaying in frigid breezes. Inside the larva waits for spring.

The warmth of spring triggers a change. Metamorphosis. Inside the gall, the larva enters a pupal stage, and then performs the magic of the insect world (think butterflies) when it emerges as a fly. Unfortunately for the fly, it is still stuck inside a gall. But there is the escape passage dug by the larva in the waning days of fall, and only a thin skin of plant tissue between the fly and freedom. Again magic happens. According to Doug Collicutt, the fly “anchors itself and pumps body fluids into a special portion of its head.” What? Apparently the top of its head balloons out because of the fluids, and this swelling pushes out through the last layer of the plant skin. It waits for its head to shrink and its body fluids to go back to their proper spots, and then the fly emerges.

Wow.

Out there past the window, past the falling snowflakes and the sap buckets collecting crowns of snow, there are larvae waiting for their moment. What a cool world.

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A recent post about Oxalis oregana and a conversation with coworker has got something tumbling around in my head. And the thumb-worn dictionary beside me is open to a word – Sentience. A sentient being is one that is conscious or responsive of  “sense impressions.” Like light? Like raindrops? You see, Oxalis species fold their leaves up in rain or excessive sun, and open them again. Sounds like a response to sensual impressions to me.

A coworker was also encouraging me to see a documentary that shows time-lapse photography of Himalayan blackberry, and — get this — how it shifts and pulls back and forth using its thorns to rip and tear at any precocious plants or saplings that might dare to attempt to grow there. Amazing to me. I had considered the thorns a hardy defense, but a weapon against other plants? I’d never thought of that. (the documentary is “The Secret Life of Plants” circa 1978 – haven’t been able to find it yet)

Some trees are known to change sex according to the sex ratio of surrounding trees. Most plants twist and turn to follow the sun. There is a constant evolution of flowers, bees, etc. I’ve heard (hearsay!) of a study where plants “screamed” (in a plant sort of way) in recognition of humans who were there to trim them.

Sentient beings. Conscious even? Definitely aware.

I attended a talk by Stephen Jay Gould a long time ago at Dartmouth. It was amazing. He spoke about evolution and the arrogance of humans. One thing that really stayed with me was the idea that as complex animals, with brains capable of self-examination, we choose to elevate beings that are more like us. His particular point was that we mistakenly associate evolution with complexity. We name the ages after the most complex animals (the age of dinosaurs, the age of mammals…) when in truth, bacteria are the most evolved creatures on the planet. And the least complex.

And how does this connect? Well, it is easy for us to dismiss the trees, for example. They are so simple. They don’t even move. Yet at the same time, they are more ancient than mammals. They’ve been around. And they are sentient beings. They react. They are aware of their surroundings.

Does a tree feel it when i brush a hand along its bark? What about when i trim a few dead limbs for a campfire? The heat of my campfire against the trunk, now that it must feel, and it probably even reacts in some way. In some way i can never understand.

It is a good reminder. Not a forest, but trees. Each one aware and sentient. It can change the way a person walks in the woods. Or wields a chainsaw. Or even a lawnmower.

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According to Pojar and MacKinnon, the redwood sorrel (Oxalis oregana) is reported to take but 6 minutes to close up its leaves, but 30 minutes to open them back up. Sounds like a pessismistic little plant to me. It is unusual, though, this sort of reactive behavior in a little plant. Quite noticeable, too. I’ve been in some hail and rain in the last few months, and it is amazing to look down and see all of the leaves folded up like retracted umbrellas.IMG_0139

And now, as the sun has been warming the woods, and i’ve had some opportunities to see various plants who’ve been suddenly exposed to more sun than they’re used to,  i notice the sorrel folded up in heavy sun, too. Pretty cool.

I’ve been in love with Oxalis for a long time. In the northeast, there is Oxalis montana (common wood-sorrel) that is different from our pacific northwest variety by having a bit more reddish color in the leaves, and reddish veins in the petals. The leaves get sort of ruddy, the way geranium leaves do. They are very pretty, and tend to blanket the forest floor in a way similar to oregana. Probably close up their leaves, too, but it’s been a while and i can’t remember.

So when i arrived in the pacific northwest, i was happy to see one of my favorite little flowers out here. What i wasn’t prepared for was the way it can glow. As i said, i’ve been in some rain over the last few months, and there is nothing like spring rain to really bring some color out in the understory.

About a month back, in the Willapa Hills, it had been raining and chilly for three days or so. We were lucky to get a sun break in the evening, that held through the first of the morning hours. I pulled myself out of my sleeping back, unzipped the tent, and went for a little morning wander as the sun was cresting the horizon. Fog filled the valley floors, and clouds shut out any hint of blue, but for a few precious moments the sun hung between the layers and bathed the ridge in soft light.

Early spring, so the understory was not yet filled with plant life, and the ground was still dark with moisture. And there in front of me was a patch of sorrel pioneering its way into the season. New leaves, dark ground, and soft light conspired to make it a lambent patch of soft green. Glowing green. It was a sight that will stay with me for a long time. Dark woods and glowing sorrel.

It’s up early in the spring, and by now there are sections of the forest floor that are blanketed in the clover-like leaves. And there is the folding thing. How does that work? What triggers it? The tapping of rain? A drop in pressure? You’ll see me out there soon, tapping one with a pencil to see what happens.IMG_0150

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