Since I live in a forest and work in a forest and spend most of my free time in forests, I see a lot of trees. But I don’t see many like these two. If two trees or parts of trees like limbs or roots of the same species grow close enough together the wind can make them rub against each other, wearing the outer bark away. Once the outer bark wears away and the cambium or inner bark touches, the trees can become naturally grafted together. The process is called inosculation and isn’t as rare as we might think. I see at least a couple of self or naturally grafted trees each year. From what I can tell these two maples had limbs that rubbed together and finally grew together years ago.
Trees that are naturally grafted together or conjoined are sometimes called “husband and wife” trees, or “marriage trees.” These two young red maples (Acer rubrum) were in the early stages of becoming grafted; it’s easy to see where they rubbed together. This can happen to most species of trees and can sometimes even happen to two trees of different families, like a red maple and a sugar maple.
Man can also graft trees and has been doing so for as long as anyone can remember. Fruit trees, especially apples, are often grafted. Many other plants like roses and grapes are also grafted onto the stronger rootstock of another in the family.
These young striped maples were entwined but not yet conjoined. Though it looks like there are three trees here there are only two. The ones on the right and left come from one stump and the middle tree comes from a separate stump. Why they grew this way is anyone’s guess but I’d say it’s a fair bet that they will all eventually become one tree. You can see how the bark has puckered on the lower part of the tree on the far right, and that’s a sign that they have been rubbing together.
Trees support a lot of life on their limbs and bark, like the many lichens pictured here. Since people see lichens growing on the dead branches of trees they think the lichens killed the branch but lichens simply sit on the bark and take nothing from the tree. They are opportunists that like a lot of sunshine though, and the best place to find the most sunshine is on a branch with no leaves on it.
I always like to look at trees like the one in the previous photo because the spots on their bark can turn out to be quite beautiful, like the script lichen pictured here. Script lichen looks just like its name suggests but it is a very ancient script, like long forgotten runes. The dark “script” characters are its fruiting bodies that produce its spores. There are many script lichen species and each seems to prefer a certain species of tree. I think this example is the common script lichen (Graphis scripta) which prefers smooth barked trees like maple and beech.
Other spots on trees might turn out to be beautiful maple dust lichens (Lecanora thysanophora.) I don’t have time to look at every tree with lichens on its bark, but I wish I did because when I don’t look closely I feel as if I’m missing something beautiful.
Target canker doesn’t harm the tree but causes its bark to grow in circular patterns of narrow plates which helps protect it from the canker. According to Cornell university: “A fungus invades healthy bark, killing it. During the following growing season, the tree responds with a new layer of bark and undifferentiated wood (callus) to contain the pathogen. However, in the next dormant season the pathogen breaches that barrier and kills additional bark. Over the years, this seasonal alternation of pathogen invasion and host defense response leads to development of a ‘canker’ with concentric ridges of callus tissue—a ‘target canker.’” Apparently the fungal attacker gives up after a while, because as the tree ages the patterns disappear and the tree seems fine.
Burl is an abnormal growth that grows faster than the surrounding tree tissues. Scientists don’t fully understand why it happens but burls are thought to grow on trees that have been weakened by stress or damage. Once the tree’s defenses have been weakened insects and /or fungi can attack and cause the abnormal growth. Woodworkers make some very beautiful things from burl and prize them highly. I find them more on black cherry than any other tree, but this example was on an old maple. It was as big as a basketball.
Trees of course are very beneficial to mankind in many ways, even medicinally. Chaga fungus (Inonotus obliquus) is a parasitic fungus that grows on birch and other trees. Though many think that the area that looks like burnt charcoal is the fruiting part of the fungus it is actually the “roots” or mycelium. It is black because it contains large amounts of melanin, which is a naturally occurring dark brown to black pigment in the hair, skin, and iris of the eye in people and animals. It is also responsible for the tanning of skin exposed to sunlight. This fungus has been used medicinally in Russia, China, Korea and Japan for centuries, and it is said to be packed with vitamins and minerals. Recently it has shown promise in cancer research, reducing the size of tumors. In Siberia it is said to be the secret to long life.
Fungal spores entering a wound on a tree can sometimes mean death for the tree. Bootstrap fungus is caused by honey mushrooms (Armillaria mellea), which are parasitic on live wood and send out long root like structures called rhizomorphs between the wood of a tree and its bark. When fresh the rhizomorphs are cream colored but darken to brown or black as they age. The fungus is also called armillaria root rot or shoestring root rot. It causes a white pulpy rot in the wood and kills many species of both soft and hardwood trees.
For years I’ve noticed that a soapy foam at the base of certain white pine trees (Pinus strobus) when it rains. Sometimes it is in just a spot or two and at other times it nearly circles the entire tree. This happens because when there is a drought or dry spell salts, acids and other particles from the air can coat the bark. Soap is essentially made from salts and acids and when it rains, these natural salts and acids mix with the water and begin to froth. The froth (foam) is from the natural agitation of the mixture when it finds its way around bark plates as it flows toward the ground.
This hemlock tree had a healed frost crack, called a frost rib. Frost cracks happen when the sun warms the tree during the day and the temperature drops quickly at night. If you’re in or near the woods at night in winter you can often hear the trees splitting and cracking, and sometimes it’s as loud as a rifle shot. Frost cracks can heal in the summer when the tree produces a new layer of inner bark to heal the wound but then can crack again in winter. When this repeated healing and cracking happens over the course of a few years the buildup of new tissue can create a frost rib like that seen in the photo.
Another example of a frost rib, this time on yellow birch (Betula alleghaniensis.) Frost cracks and frost ribs are fairly common.
Many things can damage a tree. This oriental bittersweet vine was about the same diameter as my little finger and was already strangling a young elm that was wrist size. Anyone who has ever tried to cut or split elm knows that it’s one of the toughest woods, so the bittersweet must be very tough indeed. It’s hard to know which will win this battle; I’ve seen trees with bittersweet vine grooves in their bark live on, and I’ve seen live bittersweet vines on dead trees.
Oriental bittersweet is all about continuation of the species, so it climbs up trees so it can sit in the crown and gather up all the sunlight so it can flower well. Each pollinated flower means a berry that a bird will come along and eat, and that’s how it multiplies. The young vines are shade tolerant, so when a bird sits in a tree and drops a seed to the ground beneath it the plant can germinate and live on while searching for the best path to the light at the top of the tree. Other vines like our native Virginia creeper, grapes and virgin’s bower also seek light at the tops of trees but they aren’t nearly as aggressive and don’t hurt them.
One of the strangest things I’ve seen in the woods recently is this old piece of fence connected to a tree. It has been there so long the tree has started to grow over it and if it continues the tree will eventually has a substantial piece of fencing embedded in its wood for its lifetime. Trees seem to shrug this kind of thing off and just keep on growing, no matter what the obstacle might be. The process is known as “compartmentalization of decay in trees,” where the tree uses scar tissue to compartmentalize the section with a foreign object in it. They do the same thing when fighting decay.
Though trees might easily shrug things like this off, woodcutters don’t. There’s nothing worse than running into a piece of metal with a chainsaw. Not only does it ruin the chain, it’s also very dangerous. Many things have been found in trees, including screws and nails, signs, pipes, fencing, cannonballs, bullets, beer bottles, hammers, hand saws, horse shoes, chains, ropes, stones, and one arborist even found a Chevy Corvette rim. It seems that a tree will grow around just about anything.
Sometimes scars on trees aren’t easy to explain. I’ve shown this zig zag scar on this old hemlock a few times on this blog and the consensus seems to be that it was made by lightning, but I wonder if we aren’t thinking that simply because both lightning and the scar are zig zagged. In any event I don’t suppose we’ll ever know for sure but it’s fun to guess at its origin. It comes directly out of the ground, straight for about half its length, then it zig zags for the other half. Its total length is about 4 feet.
This is a close look at the zig zag scar in the previous photo. It doesn’t look like it was made by a boy with a new pocket knife either. If you’ve ever seen anything like it or know what might have caused it there are several of us who would love to hear from you.
I can’t understand how someone can walk out of a forest and say they didn’t see anything, but I’ve heard people say it a few times. “For gosh sakes,” I always want to ask, “what about the trees!?” You don’t need to know anything about burls or frost cracks or inosculation or even what kind of tree you’re looking at to just enjoy their astounding beauty. That’s what I spend a lot of my time in the woods doing, and I hope you will too. I’ve put this post together with the thought that it might make your next journey through the woods a little more interesting.
I did not want to think about people. I wanted the trees, the scents and colors, the shifting shadows of the wood, which spoke a language I understood. ~ Patricia A. McKillip
Thanks for stopping in.
New Hampshire Garden Solutions 