Befuddling leaves and accidental tree friends

I enjoyed an unexpected pleasure the other day. It was the kind of thing that, until it happened, would never have crossed my mind as something that could be one of life’s special experiences. I was balancing on top of a big messy stick pile trying to break up some kindling for an evening fire, and as I brushed the bunches of dead leaves off the top of the pile out of the dozens floating in the air and tumbling down the sides one caught my eye. The second I saw it I broke into a smile. I watched where it came to rest, reached out gently for it, and beheld it as one beholds an old friend. I had such a strange feeling of goodwill and satisfaction. The leaf was long dead but I recognized it the same. And I don’t mean I recognized the species, I mean I recognized it, the leaf. I had spent an entire spring and summer watching it grow.

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I really did know this tree well. I had even done a series of pre leaf-drop portraits in the fall.

So far I have planted 18 trees in the back half of my yard. That’s a far higher density of trees than you’d find in almost any traditionally landscaped yard, but not excessive for a similarly sized area of deciduous forest and I want shade sooner than later. I understand some of my trees may thin out over the years, which I’m OK with. For now I’m happy to have extra plants to study and follow the growth of, particularly as they are all frustratingly small. The tallest of my new trees is an eight-foot nursery bought swamp chestnut oak, and the smallest a four-inch seed collected white oak that has been chewed to the ground by rabbits on three separate occasions. I know both of these trees and all the ones in between very well. I check them almost daily: looking for new buds, leaf growth, insect browse, and digging by squirrels. I can spend hours admiring the development of their trunk flares, perfect miniature version of what might someday be two feet of solid wood.IMG_1838

There is one tree, a two-foot oak, which I have studied more than the rest. Why? I can’t convince myself of its species. I collected it as an acorn in Iroquois Park in Louisville’s south end so it came with no identifying nursery tag, I have only vague memories of what the acorn looked like, and the leaves that have developed on the tree to this point have a unique shape. It was one of these leaves, which I spent so much time crouched over this summer, holding open guidebooks up alongside and tracing with my fingers, that miraculously jumped out at me from a whirling cloud of dead leaves.

I mentioned the tree is an oak. I actually know a little more than that, but a brief discussion of the oaks is necessary. The trees we call oaks make up the genus Quercus, and the Quercus genus is further split into multiple subgenera and then sections after that. To continue the discussion of their classification beyond this is to enter a taxanomic wormhole, so I’ll just have a quick word on their naming conventions. The two sections found in North America are the white and red groups, which is very confusing because there are individual white oak and red oak species within each section, which means listening to tree people talk about oaks can be a lot like listening to a southerner talk about soft drink flavors:

“Can I get you a coke?”

“Sure, I’ll have a sprite.”

With trees it sounds like this:

“Is that a white oak?”

“Yes.”

“Is that other tree also a white oak?”

“Yeah, that one’s a chinkapin.”

This kind of thing drives me insane. But alternative, scientific options are mouthfuls and confusing as well: red oak section synonyms are Lobatae or Erythrobalanus and white oak section synonyms are Quercus, Lipidobalanus and Leucobalanus. Yes, the white oak can be referred to as Quercus, the same name given to the whole genus.

So if we usually gloss over all the specific scientific classification why not just forget the white versus red oak distinction altogether? The two sections have an important difference in their ecological function. Red oak acorns mature over a span of two years and develop with high levels of bitter tannins while acorns of white oaks mature in one year and are much sweeter, some are even palatable to humans. Red oaks are an important forage source but animals strongly prefer white oak acorns to the point that deer will not browse red oak acorns in the fall until there are almost no acorns from the white oak group left on the ground. The primary characteristic used to distinguish a red from a white oak when you’re standing in front of one, however, is not ecologically significant, it’s just a quirk. White oak leaves are smooth all over, the ends of their lobes rounded off. Red oak leaves have bristly tips. My unidentified tree? It’s one of the white oaks.

IMG_1842Which white oak it is may be an impossible question. Part of the reason oak taxonomy is so complicated is because species in different sections of the genus readily hybridize with each other, creating individuals that are in effect gradations between species. Indeed, the genus may be going through a period of rapid global speciation, and botanists frequently debate whether different hybrids can qualify as new species and whether existing species are really just hybrids. So my oak could be a species mix. On top of this sapling trees in general are notoriously hard to identify. Seeds are great clues and saplings don’t produce any, bark changes dramatically as trees age, and young trees often develop much larger, broader leaves than is typical of their species. It is possible that in a few years my unknown tree will suddenly bud out one spring with leaves and acorns that are a textbook example of a well-known oak, but I doubt it. To me the leaves look most like white oak (Quercus alba), but they are larger than your typical white oak and the lobes too fat, chunky, and irregular. I consulted with my former co-workers at the Louisville Parks Department and they pointed out it has characteristics of overcup oak (Quercus lyrata) and I think they’re right, particularly more at some of the leaf tips. I included a few more leaf pictures and one of the buds in winter in case anyone reading this is good with their oak trees.

It’s easy to get lost in the details here, which is what I did all summer. This tree gave me the fits. Every time I decided it might be one species or another I’d notice something to cast doubt on my decision and be back at square one. I spent hours of time with this one perplexing oak. While I was feeling increasingly frustrated what actually happened is I got to know a tree better than I’ve known any tree in my life. Granted, it helped that it was only two feet tall. But when I visit those two feet to check on things it’s like feeling my way around my bedroom in the dark. I know every bump and detail from ground to tip. Sitting here now I can picture where it got gnawed on by some animal early last spring and how that’s healing over, I can envision the gentle trunk flare just starting to be pronounced at ground level, and I can hold my fingers at the angle the one little branch splits off from the central leader. Of course, I also know those leaves.

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Sadly, the other part of the equation that allowed me to pick one leaf out of a pile is that there are few oak trees in the neighborhood around my yard and the ones I know of are the distinctive and excessively planted pin oak (Quercus palustris). With the natural variation in the thousands and thousands of leaves from just one mature tree the notion that you could individually recognize leaves from a common species on the ground in a heavily wooded area is absolutely ludicrous. We don’t plant near enough oak trees. Among the most important ecological tree groups in North America, and certainly in the eastern deciduous forest, oaks are climax trees. They pierce canopies, live hundreds of years, and provide a major food source for wildlife. They also grow slowly, which is probably the biggest gripe against them by homeowners. Well, there are prices for strong wood, stable shade, and longevity.

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Of the 18 trees I have planted thus far seven are oaks. I’m pretty impatient for the day when I can’t pick a leaf from one of eastern North America’s most widespread and common genera off the ground and confidently identify not just the tree it came from, but the twig. But there’s nothing like a growing oak to remind one that the world runs on many time scales and the human scale is just one of them. It’s year one in my yard and a new generation of trees have literally left their mark on the landscape; their small crop of leaves wedged in other stick piles or folded under grass. And I, trying to obsess over naming, labeling, and the quantification of everything back here, became acquaintances with a tree that barely reaches my knee and may live longer into the future than our city has yet existed and certainly far far longer than my physical body will persist. This tree’s final few buds may burst open some distant spring morning using as fuel my body’s by then thousands of times recycled nutrients and long dissociated chemical elements. It is good to be on friendly terms with such members of the world. Standing on the stick pile I held on to the leaf for a few minutes. I had an impulse to try and preserve the rare moment by setting the leaf in a box on a shelf or pressing it between the pages of my tree field guide. But the beauty of such a moment is ephemeral. Over time if there are enough of them they just become part of a place and your relation to it. I snapped a few pictures and let the leaf tumble away in the breeze, certainly never to be encountered again as it begins in earnest the process of decomposition into millions and millions of microscopic organic particles.

There's a leaf we know in there. I said the stick pile was a mess. Like a fool I kept piling fresh sticks around the edges so to get the good dry stuff you have to wade into the middle.

There’s a leaf we know in there. I said the stick pile was a mess. Like a fool I kept piling fresh sticks around the edges so now to get the good dry stuff you have to wade into the middle which, of course, is how I found my old summer leaf friend.

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