The spruce plot and marcescent southern oaks

January 18, 2017

This morning was cold, damp, and murky. Biking in from the gate I could see about 30 feet by the headlight. The mist streamed steadily through the light, racing downward and toward me as I rode. I biked west to the eastmost shortcut road, which is gated off in the winter. The unused road past the gate pitches downward through the woods. Last week’s storm scattered branches over the pavement. I locked up at the walkway and headed east. I’ve walked or skied this trail many times, but picking it up at this point, in the middle, gives me a strange feeling. The woods directly to the east remind me of trails in the Finger Lakes region of New York where my wife grew up, dominated by red oaks and sugar maples, with American beech and ironwood and Carex platyphylla underfoot… the last of these species is missing here, but white bear sedge takes its place. Looking at the distribution map for the species in New York, I see the two counties flanking my wife’s birthplace have herbarium vouchers for the species, but her county does not. I ought to have collected it last time I saw it.

I hiked into the spruce plot, a foreboding place before dawn. This dark, monotonous monoculture of spruces planted in a rectangle with sharp margins doesn’t have a lot to recommend it in the day, at least during the growing season—mosquitoey from June onward, nothing to speak of growing in the understorey—but this foggy morning it was transporting. A little stream babbled on my right, nothing moved. The spruces towered above. I could have been on the Apostle Islands in November.

Coming out of the spruce plot was a bit jarring. It wasn’t yet six, but the glowing sky seemed awfully bright. I crossed the road and hiked up a slight rise on the other side where I found Carex woodii in my first year at the Arboretum. I looked around with the flashlight and found plenty of Pennsylvania sedge and something much greener, but no C. woodii that I could see. I’ll find it this week: it’s lurking along the edges of the road, distinctive with its bladeless, burgundy leaf sheaths and tall shoots. I’d like to see it in midwinter before the snow returns.

Hiking around the corner to the oak collection, I was struck by a few very small trees that were utterly marcescent. While many oaks, especially the black oaks and their relatives, have some marcescent shoots, basically all the trees in the collection have dropped the lion’s share of their leaves. But on these few trees, it appears that hardly a leaf fell in the autumn. Two are southern species—post oak and blackjack oak—and one is a widespread east Asian species, Quercus mongolica. Out of place, I could easily understand this degree of marcescence as a maladaptive consequence of evolving further south. But the fourth species is our common black oak, accession 185-92. When I returned to the building, I expected to find that the accession was a southern collection, something from downstate Illinois or the Ozarks. It turns out, however, to be from Merioneth Drive just east of Crete, Will County, Illinois. That is south of us, but less than a 1-hour drive. Can that be enough to explain the phenotypic difference? Victoria Sork wrote an arresting article in American Naturalist in 1993 showing local adaption to herbivores in red oak on the scale of 100s of meters. The article floored me at the time: knowing how far oak pollen moves, I had assumed that oaks would exhibit little if any local adaptation. It may be that a Will County population is just different enough to behave as we see in our oak collection. On the other hand, it may be that what I’m looking at is just young oak behavior (though I’ve listed all the young oaks I observed this morning to be marcescent). I need to keep my eyes peeled. I have another two months or so before the trees start going again. Once secondary growth starts up, the leaves are likely to drop.

I hiked the remaining distance to my bike. It was 6:20 by now, but still foggy enough that the sky wasn’t growing light very quickly.

Old oaks

January 16, 2017

It was just above freezing this morning; sidewalks and driveways were glazed with ice. The road through the Arboretum is not particularly nice on mornings like this. I walked my bike along the base of the woods where I had walked out last week. There are even more big old sugar maples than I had realized out here. When I interviewed for this job 13 years ago, I asked on a drive-through with the director of research whether there were a lot of maples at the Arboretum, and he told me I was driving through a sugar maple forest right at that moment. It was January, but all the same I could not have impressed him. We were, I believe, at the very turn where I was carefully walking my bike this morning: today, I felt all I could see was great big sugar maples. These trees are magnificent, messy-headed beasts as wide as a window frame, heading straight up and then bursting into a crown of branches at the top. Their bark is grey and platy, and their trunks are massive, heaving out of the soil. I leaned my bike against several trees to walk up and look at this maple or that one, seeing the bark as though for the first time. Tom Brown tells a story about being instructed to study the robins. He protested that he’d seen robins enough already. He was asked, “how many spots on the robin’s breast?” Of course he couldn’t say. There’s always more to see.

Naturalists tend to be both romantic and realistic in this way: there is always more to see in the tree that you’ve walked past a thousand times, or the patch of forest you’ve biked through so many times. I estimate that on my bike rides into the Arboretum since we moved to Downers Grove I’ve biked this particular turn at least 750 times. That’s a sobering statistic. As I walked through this morning, I saw as much as I might in a forest I’d never visited before. How many big old sugar maples at the northeast corner of the road through the East Woods? I hadn’t thought before today of the fact that I couldn’t even answer that. We tend not to see much when we don’t have questions. Forget your curiosity and you won’t see anything new. The naturalist’s romantic streak shows in the notion that we can look at the same individual over and over and always see something new. We can, but only as long as we stay curious and keep asking questions.

I parked my bike at the Big Rock Visitor Station and walked the heritage trail clockwise. The trail traverses a moraine that looks over a couple of kettle ponds to the south. The larger one pond I botanized once: it is surrounded by bur-reed and rice cutgrass and clearweed, and it is filled with bladderwort. I had not expected to find bladderwort in such a pond, but there it was, festooned with little traps. Why do we find bladderwort with its traps in these rich ponds, when it must be so costly to build the traps? Perhaps traps are easy to build. Perhaps they just confer so much benefit that it’s worth growing them wherever you are. Perhaps the bladderwort got there first. The smaller pond today was frozen solid, branches emerging from the surface of the ice. I walked out to the middle of it, turned slowly, then walked back to the trail and sat for a minute. The traffic on I-88 hummed. An Arboretum truck trundled by, snowplow raised. The mallards and the Canada geese started talking. It was 5:49.

I rarely walk this trail and had taken it just for a change of pace. I recalled it as a shrubby, overgrown secondary forest, and I half-expected to just walk briskly through on a roundabout way to the Big Rock. But when I came down the hill to the westmost turn in the trail, I realized I had underestimated the place. There were perhaps a dozen bona fide open-grown bur oaks, branches stretched out, wide-crowned, towering over the brush beneath. Against the glow of the cloudy sky, the oaks are unmistakable, hearkening back to before European settlement. Why did they persist here? Why weren’t they cut down? How old are they? What is coming up beneath them with brush-cutting and fire? About 10 years ago I was part of a project that assembled the land-use history of the East Woods, but I and my staff were focused exclusively on vouchering the flora. I obviously have some reading to do. I walked on and crossed a beautiful bridge, read a sign about the bur oaks. I’m essentially a first-time visitor. I’ll be in the habit now of watching this place more often.

I made the final turn around the end of the trail and headed back up the trail, parallel to the boundary road and northeast end of Eagle Lake, came to the Big Rock, where my sons and their friends built a little shelter two years ago, back out through the oak forest to the parking lot, and back to work. Geese were still cackling. Rain had started, and I was glad to get back to the building, slip out of my shoes and get a cup of coffee. As I finish writing this, I read that the roads on the east and west sides of the Arboretum are closed due to the ice. This means more walking, less biking and driving. That’s not so bad.

Fallen trees and tree silhouettes

January 11, 2017

This morning I locked my bike up at parking lot 10, on the southeast edge of the road going around the East Woods. The woods there are dominated by large old trees, all silhouettes an hour before dawn. I was hoping to find a tree that I heard fall as I was biking out last night. I had left at about 4:30, and the wind was ferocious. Somewhere between P10 and P8, I believe, I had heard the unforgettable sound of a great tree cracking and then falling through the woods, crashing through other trees on its way down. I’ve only once seen a tree of this size go down, in a red oak woods in Madison about 20 years ago. It had been the same sound: a substantial crack that could only be from something very large breaking. The sound was riveting, and I looked around rapidly to see if I was in the way… I had no idea where the sound had come from, but it was close. Then I saw the tree about 30 feet away, falling downhill parallel to the trail I was on. It fell like a dancer falls, arched legs and back and arms, until she catches herself in a short run. But of course the oak kept falling, knocking through maple saplings and scraping the bark off nearby trees until it hit the ground and bounced, slowly, as a massive body must. The tree had broken off perhaps 15 feet above the base, and the wood was wet and ragged, twisted in the places where it was still attached. The bark sloughed off like soaked flannel, sagging and buckled at the edges. The ground around the tree was remarkably undisturbed: wildflowers and sedges and leaf litter was mostly intact, with only occasional broken spots where a branch had punctured the ground. The bark on the trees the falling oak had struck was scraped off cleanly, and the exposed wood was fresh and white. Since then, I have felt that every fallen tree in the woods is a near-miss at watching another tree go down. I hope to see such a thing once more before I go.

At the top of the hill just south of P10, the oaks all appeared to be forest-grown, not a lot of knobs of lower branches broken off after decades of growing in the sun. There were branches on the ground, some large enough to trip you if you weren’t paying attention, but no large trees across the path, and nothing newly fallen of any size that I could see in the woods around me. Walking down the hill, the white oaks increasingly pick up short, skinny lower branches, decorated with marcescent leaves. Tree after tree showed this pattern: a naked crown and young branches that had retained their leaves after the life was out of them. This is not uncommon in oaks, and it stands out better at night. Why do the trees do this? Is there some advantage to trees that exhibit marcescence? And why the younger branches, unless marcescence is just a developmental side-effect, a failure to get all the way to the abscission layer in the fall. There may be nothing deliberate about it: it may be a textural artifact on an otherwise functional tree, no more functional than thinking wrinkles.

At the bottom of the hill, just east of parking lot 8, the woods open to the south, grading from forest to savanna to wet meadow. I picked my way through to the edge of the Phragmites and reed-canary grass meadow, then walked to P10 and crossed the road. I grew restless and turned on my flashlight, exploring initially for sedges. Hunting for sedges is my go-to activity outside, and it’s reliable fun in almost any season. I found Carex blanda and C. albursina, and a whole mess of something I should know but couldn’t put my finger on. I know there should be flocks of C. hirtifolia out there, but I didn’t see any. It may be that this is one of the odd woodland sedges that is not semi-evergreen. There’s work to be done on this.

I prowled and scanned on the forest floor and was having a great time out there in the dark, when I suddenly realized the tree I was looking around was a cottonwood in the middle of the oak forest. I turned off my light and looked at the bark, turned it back on and searched for cottonwood leaves among the white oak and sugar maple litter at the base of the tree, looked for the great buds on the branch tips above. Why was I surprised by the cottonwood? Should I be? I’m always unduly influenced by my own typically too-narrow experience of plants. Jason Sturner collected a cottonwood specimen northwest of the Big Rock Visitor Station in 2007, and presumably there are scattered cottonwoods elsewhere in the forest. I’ve just not noticed them, or I’ve noticed them and not given them enough thought to remember having seen them. This tree was perhaps 2½ feet in diameter, which is not particularly large for the fast-growing cottonwood. I gather that it established in the shade under the oaks. I have something else to keep a watch for this year.

On my walk out, I my full attention to the standing trees, and I was now all the more happy to have the flashlight with me. I kicked around among the white oaks, the red oaks, the sugar maples, studying silhouettes in the dark and bark by flashlight. The old maples seem to have branches that diverge more near the crown than the oaks of the same height and diameter. I worked my way back to the easternmost edge of the woods, came up to the road from the forest side. There was a fallen hop-hornbeam, quite old, but no big trees. There was the stump of an oak that must have fallen over a decade ago, sawed off to get the trunk off of the road, but nothing newly fallen.

Wherever that big old tree was, I didn’t run across it. Dawn was coming on by the time I got back to my bike, and I left my light off as I biked through the clearing towards work.


Addendum, 4:30 p.m. On the bike-ride out later that day, I found what I suspect is the tree I had heard snap off in the wind. It was to the north of the road, not to the south, a white ash riddled with fungus, ca. 1.5 ft dbh, broken off about 6′ above the base.

Fields of view

January 9, 2017

I worked for two semesters during graduate school as a teaching assistant for Dr. Ray Evert, a brilliant and delightful human, a great plant anatomist. He was an inveterate and enthusiastic observer. Almost every lab I taught he was right there beside me, walking around and helping the students interpret what they were seeing. He peered through every scope, continually teaching and reteaching students to focus and perform Kohler illumination, helping them to interpret what they were seeing. Our field of view in the course tacked from less than half a millimeter to the whole plant. We waded into microscopic worlds with Dr. Evert by our side, jumping into a slide disoriented, blind to everything outside the sharp-edged circle of light that we navigated around the slide, uncertain as to where we were. Often it was frustrating, spending inordinate amounts of time simply not seeing what we were looking for. But then suddenly we would find it, or realize that we had been looking at it and could only now see it and understand what the drawing on the chalkboard earlier that day had meant. We traversed the length of a vessel cut lengthwise from a tree trunk 40 years earlier or digested out of a tree trunk in bubbling lye, then switched slides to stare end-on down another vessel cut, most likely, from the same tree. We drew, looked again, erased and redrew, thought back to the chalkboard drawings on the board, considered what Dr. Evert had put into those drawings and what he had left out, most likely deliberately. We went back to the scope, did more drawings, then occasionally glanced out the window to give our eyes a break, watched a tree branch shudder under the weight of a squirrel leaping, vessels creaking against each other.

A colleague is coming into town in a few weeks, and we’re going to spend the day hunting sedges for a winter-root study he is conducting. He wants the plants frozen, and it looks as though he’ll get his wish. On my bike ride in this morning, I had in mind to start relocating populations I know of that he might like to see. I turned off my light and walked to a trailhead where I know I can easily find five species. Within a minute, I could see well enough to get around and know where I was in the woods, but it was still nighttime, and I couldn’t see any sedges. Flipping on my light, I gained a 3-foot circle of visibility at my feet. Sliding my flashlight circle around on the forest floor, I found Carex hitchcockiana and a little colony of Carex jamesii. I found, moreover, that the Carex jamesii is more widespread than I thought, covering more of the ditch bank than I had noticed in summer. The leaves were green, despite the fact that temperatures have been well below freezing for at least a week, maybe more. I pulled off the edge of a few clumps to bring them back to the herbarium, looked at them closely under my light. Around me the great East Woods was all but invisible to me: coyotes and foxes, deer mice and meadow voles, white and bur and red oaks, puffed-up chickadees and nuthatches, cardinals ready to burst into song in the clear morning, torpid skunks and raccoons and chipmunks, woodland sunflower stalks, carpets of oak leaves and patches of snow and heaps of decomposing tree trunks. All I could see was the sedge in my hand.

I switched off my light, squeezed my eyes shut and reopened them. The East Woods was back. I pocketed the sedges and walked back to my bike, surrounded by oaks and sugar maples. I much prefer the woods at night without a flashlight. I biked for about 30 seconds before I remembered to switch my light back on: you can see well enough by night, but not that well. In my office I flipped on the computer to start writing, and I remembered something Dr. Evert had said to me in one of the interstices of the anatomy lab, when the students were all working quietly and we were waiting for a moment of need. There were a few such in every lab, and we were often quiet during them ourselves, but occasionally we’d swap short anecdotes or memories or jokes. During one of these Dr. Evert had told me about meeting Saul Bellow, asking him how he had come across Katherine Esau’s Plant Anatomy, referenced in one of Bellow’s books. During another, he had told me a good Groucho Marx line about a fly crawling up a wall, but I cannot remember it now. What I remembered this morning was an emphatic and puzzled observation Dr. Evert had made about computers. Dr. Evert, to my recollection, had a typewriter and a microscope and books and files in his office, but no computer. How, he asked in that lab, could people get any work done when they were pulled into the computer all the time? When he walked through the halls, he’d pass colleague after colleague staring into his or her monitor. There was something devouring about it, too captivating. Walking past office after office that week, I looked in and saw too that everyone was staring at his or her computer.

As I switched my computer on and started writing this morning, the day opened up outside. The sun came up, the birds started moving, and I had my coffee and wrote. At one point I pulled out the sedges I’d filed in my pocket and put them under the scope, to see if the bases looked as they ought to for C. jamesii. The whole business of seeing the world works like this, tacking back and forth between fields of view. You see what’s inside the field, and you make the most of every field and you tie the fields together. That’s the fun of it. It would be no fun at all with only a single field of view.

Lights at night, from a distance

4 January 2017

I arrived in the East Woods today during astronomical twilight, still dark enough out to see the stars clearly, but I could see the day brightening as I walked in. From the furthest bend of the road going through the east woods, the lights of the suburbs and the business park to the north and northeast reminded me of coming into Las Vegas at night 25 years ago. I was 21, sitting in the back seat, a hitchhiker with a tall eastern European medical student who was also hitchhiking, living on white rice and raw bacon and ketchup and cream cheese (an unlikely but delicious combination), scouring used book stores for medical texts he couldn’t find back home; a 17- or 18-year-old kid from Texas, our driver, who was out to see the world before heading off to the military; and his German exchange student, who was sharp and a bit exasperated. I believe the boy’s parents had sent him and the exchange student off with the car and a gas card to see the west. He was nostalgic as all get out, compulsive, young. It was dark, and I had just caught a ride out of the Canyonlands and Zion and Arches. I was in the state you feel coming off the trail when you are suddenly back in the car, and your campsite of that morning is locked up instantaneously in the past, inaccessible to you, and you are a little stunned. What were we doing going through Las Vegas? I can’t tell you what I was feeling the second before we saw the city, but I remember the feeling of buoyancy as we came up over the hill to the east of Las Vegas on I-15, and I suddenly saw all those bright lights in the distance, orderly stars crammed into the gridwork of the streets and sidewalks. Peering over the shoulders of the guys in the front seat, I was flying through the west. I had once previously experienced this feeling, in the foothills of the alps in southern France, watching the lights of the houses on a far slope grade almost indistinguishably into the stars above. Both times, I felt I could jump and land among the lights with just a little push off.

I biked to the trail that leads west from the Big Rock Visitor station and walked the remaining way into the visitor center. I had in mind to start making observations of the woods today as a backdrop to a book on the American oaks – I think every year of my adult life has started with some vague plan of this sort – but I hadn’t reckoned on it being so dark. Trails stretch out when the sun goes down, and everything looks new and strange. I like walking in the woods, and I think a part of me will always have faith in a romantic fantasy that my senses will pick up where my eyes leave off, and I’ll be able to just sense the species I’m walking past. That of course is nonsense: the only way to make that move from one sense to the other is through work, taking the time to learn an individual during the day, get to know it well, then come back to that individual at night. At night, I find I am much more taken by the woods as a whole than I am by individual trees. A few individual trees grab my attention as I walk by, but I more impressed by the sound of the bike wheels rolling over the frozen chips, the structure and texture of the woods around me. I stopped at a bench overlooking one of the little ponds that appeared on the east side after the drainage tiles were smashed around 2005 or 2006. It was now what they call nautical twilight, and the early morning breeze was moving frozen things around a bit. Birds were still: I thought I heard something calling in the distance, but only once. It was only 12 degrees Fahrenheit, but I still expected to hear a bit more.

I walked on toward the visitor center, came up over the hill by Marlin Bowles’ lime prairie at the corner of the geographic collections, and off across Meadow Lake stood the illuminated trees that the Arboretum strings up each year. I was looking toward the west edge of the lake, to the very spot where three nights earlier my family and I had been standing, and my sons had gotten into a conversation about whether or not the lights constituted a work of art. One claim was that strings of lights should not, under any condition, be thought of as art; the counterclaim was that hung in the bedroom, those lights would just be lights, but out here, strung across the lake and up in the trees, they became art. I stayed out of the argument, but this morning as I walked the remaining quarter mile to my office, I watched the trees in front of the visitor center as I approached and then walked under them, and I was struck by what the lights accomplished. The lights so carefully track the architecture of the trees that they bring out some essential aspects of the structure that I would not have seen in the daytime. Like a fluorescent dye administered by a doctor, or a stain used by a cytogeneticist, the lights highlight the trees’ structural essentiality. From a distance, the artificial colors (blue, white, electric green) reveal one person’s understanding of the tree’s essence. Like the lights of the suburbs, or of Las Vegas, or of a village on hillside, the lights on the trees provide an insight into the architecture of the world that is harder to put our fingers on in the daytime. A walk at night, for me, highlights the structure and texture of the landscape much more than a walk during the day, when individual trees continually distract me.