Two curious trees

Path of lightning strike

That is to say, two strange and interesting trees (I doubt the trees feel all that much curiosity, although we do suffer from something of a language barrier, so who’s to say, really; it’s probably a little presumptuous of us to think we know what they’re feeling). I spotted this first tree the same day I returned to the beetle-hole-turned-sapsucker-well grove over at the 100-acre woods; it was the subject of my pushed-luck photos, the ones I managed to take following the resurrection of my camera battery. I wouldn’t’ve been heartbroken had the battery returned to the dead and I’d been forced to return home without the photos, but I did stop and puzzle over what I was seeing for a few minutes.

What caught my eye, initially, was this ridge that seemed to run along the side of the trunk. It was about two inches wide and nearly the same high, sticking out from the trunk proper. It looked an awful lot like the thick trunk of an ancient climbing vine, a Virginia Creeper or grapevine (our Poison Ivy doesn’t climb here). It took close examination to convince me that it wasn’t external to the tree (or previously-external-but-now-being-grown-over). No, it actually appeared to be an old wound, now healed and thick with scar tissue. The fact that the ridge broke and jumped slightly sideways at eye-level confirmed that it wasn’t (or hadn’t been) a vine.

Intrigued and still puzzled, I circled the tree and followed the ridge as it rose up the length of the trunk – in a spiral, all the way up to where the branches started, thirty or forty feet from the ground. Any guesses?

Twisting path of lightning strike

I believe this is the scar left from a lightning strike many years ago. I wrote a whole post about how lighting works a few years ago (I initially wrote a couple, and then realized it had been longer than that; I’ve been blogging more than three years. Goodness.), after a tree behind my parents’ house had been hit and destroyed by a strike. Trees are often hit by lightning not just because they’re tall, but also because they’re wet – whether on the outside, from rain, or the inside, from sap – and therefore conduct electricity extremely well. The lightning, once it reaches the tree, takes the path of least resistance. Although this can sometimes be down inside the heart of the tree (as it was for the pine), usually with disastrous results, it can also (perhaps more often) be down the outside of the tree, either through the water that’s soaked the outer bark, or through the sapwood just under the bark.

While lightning traveling the outside of the tree will likely do little damage beyond superficial burns, if the electricity enters the tree it can be more problematic. Lightning is incredibly hot, even hotter than the surface of the sun (which means little to most of us, since none of us have been there to experience it firsthand, but does at least give you the understanding that lightning is really, really hot). It should come as no surprise that any liquid that comes in contact with lightning is instantly vapourized. When the lightning travels through the inside of the tree, through the sap, the sap is instantly vapourized, turned into a gas. Gas takes up more space than liquid – it’s all the same atoms, just spaced a whole lot farther apart (yes, you can have solid/frozen oxygen, if you can somehow get the temperature down to −362°F/−219°C) – so you can imagine what effect this has if the liquid had been in a confined space. Yup, that’s right: kaboom.

If the lightning travels through the outer sapwood, rather than down through the heart of the tree, the effect is the same, but less pronounced. The outer bark and probably the layers of sapwood (the phloem and xylem) will be stripped along the route the lightning takes, but the rest of the tree will remain intact. As the tree heals over the open wound, it will inevitably form a ridge of scar tissue, and that’s what I think I was seeing here.

Dead tree with twsting wood pattern

Why the spiral, though? Well, although we can’t often tell from the outside, under the thick outer bark the inner wood of the tree is sometimes slightly twisted. It’s easiest to see this on dead trees where the outer bark has all sloughed off over time. This is such a one that I found last fall, for instance. I’m not sure what caused the two wood colours, but it does help to make the twists and waves of the trunk pretty obvious. As you can see, the wood doesn’t necessarily grow straight. Some trees have a very pronounced spiral. (I do actually have photos – somewhere – of such a dead trunk, but don’t ask me to find them.)

So what I think happened, why I think the lightning traced a spiral route down the tree, is it was simply following the path of the bark. Pretty neat. The tree seems to be doing well these days, despite the incident.

Broken and healed limb, pine tree

This tree I’ve seen a few times. It’s also over at the 100-acre woods, but at the edge of one of the fields. I’ve walked by it a number of times, and when I photographed it a couple of days ago, it wasn’t the first time I’d noticed it. In fact, I think the first time I’d consciously taken note of it was during the winter; this year or last, I can’t remember. I do remember, however, thinking that the branch had been torn in one of our ice storms. Pines seem particularly susceptible to this sort of damage, because they have so many long needles which catch not only ice but snow, and because they’re a softwood, and their limbs aren’t quite as sturdy as, say, a maple or oak.

So I’d noticed it before and not thought too much of it, but when I walked by the other day I realized two things: first, the limb was still alive, and second, that it wasn’t even a recent, open wound. Looking more closely (below) it’s obvious that this happened quite some time ago. Not only is there no recent wound, there’s barely any evidence of a wound at all. Like the lightning-struck tree, the damage was minimal; the pine’s limb was still connected by enough tissue that it simply grew over and sealed the wound, and carried on.

I love seeing resiliency in nature.

Broken and healed limb, pine tree

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10 responses to “Two curious trees

  1. I have seen lightning strikes on a tree trace odd patterns. This appears so vine like a damage perhaps the lighting ran down a vine. Don’t know if that is possible. We had a terrible ice storm in 2009 here in Kentucky damaging trees over hundreds of miles. We have two cedar trees that look like this second tree in our pasture. Old cedars that were once bush hogged then grew back like a couple trees together. The ice storm broke down a section but enough connection remained for them to continue growing and healing. It is interesting how the trees have a great deal of sprouts that are replacing broken of branches and tops to retain their balance.

  2. LOL. I was thinking the thoughts you opened with as soon as I saw your title.
    You’d think we were related. Interesting post.

  3. Amazing how trees can show you their history if you take the time. I also think that’s a pretty amazing photo—so tall and narrow, it shows the whole trunk and still fits on the page!

  4. There was a similar spiral ridge on a fallen cucumbertree at Cook Forest State Park, PA. Will Blozan, President of the Eastern Native Tree Society and of Appalachian Arborists offered a different explanation: The ridge appears to be a fracture that severed the cambium. The spiral is
    just the orientation of the wood fibers in the tree. Continued flexing along
    the fracture does not allow the cambium to fuse together again into a
    continuous layer across the fracture. Thus, the wound-wood tissue simply
    “plows” into its respective counterpart on the other side of the fracture
    and builds up a ridge of wood. This can also be seen when a tree tries to
    swallow a rock. Sometimes these fractures do close again but the ridge will
    remain for many years if not indefinitely. Regardless, the wood is fractured
    underneath and trunk failure is likely. http://www.nativetreesociety.org/fieldtrips/penna_cook_forest/cook_nov18_2005/cook_forest_cucumber.htm

  5. Intrigued and still puzzled
    trees

  6. Glad I’ve finally found soemnthig I agree with!

  7. this is so interesting… i have been wondering about lightening strikes on trees so a bit of serendipity here!

  8. Interesting – I hadn’t thought before about the mechanics of how a lightning strike damages a tree. Very observant of you to figure all this out.

  9. a fascinating read…thank you. shows the inherant strength and healing abilities of these wonderful beings xx

  10. i love this blog. thank you for sharing all of this.

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