My Year of Observation

My neighborhood.

--is what Henry David Thoreau wrote in his journal in July 1852, as he sought to pay special attention to the animals and plants he encountered.  This from a man who observed continually in his own community, once wryly observing, “I have traveled a good deal in Concord.”  For much longer than a year he meticulously recorded the flowering and leafing-out of hundreds of flowers, shrubs and trees.  (So meticulously, that his recorded observations have been profitably mined for comparison with modern data, documenting the changing climate.)

In the year or so since I began to track the phenology of some of my local trees, I have also been more careful, patient, and observant.  Lately I have mulled over how different this year feels from last year, and the reasons for it.  Last year I was often confused, often waiting for things that did not occur, and simply ignorant of basic facts—an amazing thing, considering how much information is just a few clicks away. 

 

Red maple in bloom last year.  

 Sugar maple April 28 & May 3 of last year.

 Once the leaves have expanded, samaras seem to disappear.

Only the occasional fallen twig or aborted samara shows they're still up there somewhere.

Last year I watched the red maples flower, leaf out, set fruit, and scatter its offspring in a neat sequence that you could almost set your calendar by.  Looking at sugar maples a bit later, I watched them flower and leaf out, then wondered why I didn’t see samaras.  Perhaps these were male trees.  When samaras began to appear on the ground a few at a time, I considered that the sugar maple, which is a northern tree, might be too near its ecological limits to reproduce efficiently. 

Same sugar maple branch a year later.
Samaras ripening on July 23.

This year I have learned to find samaras buried among the leaves if branches are low enough and you look for the right angle to show them up.  And this year there are a lot of samaras up there.  I also learned that sugar maple, unlike red maple, has male and female flowers on the same tree.

Last year I didn’t discover silver maple until the spring was well underway, and did not know when it flowered.  Now I know that it is among the first trees to do so; I watched it flower this year, along with quaking aspen, which also wasn’t on my radar screen last year.

Silver maple began to bloom on April 6th.

I discovered ash-leaved maple, already with well-grown samaras, on May 23rd.

This year I am watching two maple species I didn’t even know about last year: the weedy native Ash-leaved Maple, and the alien Sycamore Maple.  It was well along in the growing season before I discovered them, and next year I will be able to put them in their place when I see them flower.  I also have more individuals of each species to keep an informal eye on.

I saw sycamore maple only on June 5th.  Besides having toothed and more

strongly-ribbed leaves than Norway maple, this alien has samaras are often in threes.

Ashes had me even more confused.  I have never seen any samaras under the stately white ash in my back yard.  Yet there are several white ash saplings in the woods only a few yards away.  Last year I watched carefully when it began to spring, but could never say what happened to those flowers, or even their gender.  Sure they were up there somewhere, I waited in vain in fall for samaras to appear on the ground; they never did. 

This year I discovered a couple of ashes at the high school with branches low enough to look at closely.  These were male trees.  Early in the summer I happened upon a prolific female ash directly across the street from other trees I was observing.  Although the branches are a bit higher, they’re well within reach of my camera, and show me what I might expect from a healthy female.  I found a couple more recently, but these new females are in poor health—another issue to watch.  

My beloved white ash right now;

The female ash a few blocks away with some of her many, many babies.

Last year I watched male catkins erupt on all the oaks, but had no idea what the female flowers looked like, and never saw any acorns on the branches I was watching.  Again, I wondered why, and speculated that city living wasn’t good for oaks. 

This year nearly every oak in the neighborhood is laden with acorns.  Although this is a real change, it’s also true that I’ve learned how to look for them: acorns are nearly invisible when branches are viewed from the side, but from the ends and especially from beneath they can be spotted.  Lighting is also important. 

 These black and white oaks have low enough branches

 to track the growth of acorns easily.

More commonly, I take zoom photos of higher branches,

and then enlarge them further (red oak).

Oaks of the red oak group (those with bristle-tipped leaves, among other distinguishing features) have been transforming before my eyes this year.  Last year I believed that most of these oaks were hybrids among several species, and that true examples of pure red, black and scarlet oaks were rare in the neighborhood.  I thought so because I found scarlet oak leaves on trees with black oak buds, and so on.  This year I learned that hybrids are relatively rare among oaks, but their features can vary quite a bit.  Now I believe my neighborhood oaks are probably all card-carrying members of their respective species, but I still lack the confidence to assign them to those species.  In particular, the neighborhood may be full of black oaks and empty of scarlet, or the reverse—I simply don’t know.  The crop of acorns coming up may help distinguish them. 

Those acorns have been another part of my education.  Oaks of the red group differ from those of the white oak group in having acorns that take two seasons to mature.  Now I have seen this development up close: the female flowers are very small and borne in pairs in the axils of the leaves, looking at first much like buds.  Meanwhile, fruit begun last year is developing and growing on last year’s twigs, looking more and more acorn-like as the summer progresses.

One further change.  I began by observing a one-mile route, and made the bulk of my observations on trees I was watching for Nature's Notebook.  Branching out, I discovered other species and--just as important--found new individuals of trees I thought locally rare.  I began observing just two silver maples, one ash-leaved maple, and one shagbark hickory.  Now I have three or four silver maples to compare, three stands of ash-leaved maple spread over a mile, and several shagbark hickories in neighborhoods almost a mile apart, and several fertile female white ash trees among the dozen white ashes I know.  I now walk three different routes with the dogs, each taking us in a different direction.  By walking them in order, I ensure that most plants get a good look about every three days.

Overall, I know so much more than I did a year ago, and with that knowledge comes a certain confidence.

Paying Attention

Nature will bear the closest inspection.  She invites us to lay our eye level with her smallest leaf, and take an insect view of its plain.      Henry David Thoreau

I took a field botany (plant identification) course back in about 1980 at the University of Rhode Island with the famous Elmer Palmatier.  I stumbled along with a couple dozen others behind the Master (who, as always, wore his jacket and tie), struggling to collect plant specimens and absorb his comments before we were left behind.  We would return from our little field trips with about twenty five new specimens to dry to mount to make identification flashcards.  (Thirty-five years later those plant cards are still in occasional use.)  Then we would have to memorize these plants--common name, Latin name, and family--before the next quiz.  On Saturdays professor Palmatier would lead plant hikes for anyone interested.  By summer's end, I could (sort of) identify almost three hundred plant species by sight.  I was pretty pleased with myself, and that pleasure has not entirely abated--though I've forgotten most of them by now.

Lately, though, as I've paid close and regular attention to a handful of species, I've learned much more.  Most of it is undoubtedly available on the internet, and I haven't been shy about consulting web resources, but I've benefited most from simple hands-on observation of real plants. 


What has acquaintanceship with trees brought me?

 

Basswood (Tilia americana) has flowers with all typical flower parts, both  male and female.

 

Flowering dogwood (Cornus florida) had small flowers

clustered tightly, but four large bracts around the flower cluster

fool people into thinking the whole cluster is just one large flower.

Grass flowers have an intricate, delicate beauty--even with no petals--

but you need to look closely to appreciate them.  Orchard grass (Dactylis glomerata),

panic grass (Panicum virgatum), and big bluestem (Andropogon gerardii).

I've become familiar with the flowers and fruits of many species.  In the spring of last year I waited for trees to flower, but was not always sure what I would see.  Some trees showed no flowers I could see, but produced fruit later.  Others produced nothing.  In particular, the long, swinging, male catkins of oaks color the whole tree tan in spring, but there are no apparent female flowers.  Observing fallen twigs, I discovered that female flowers are shy, retiring things borne singly or in pairs in the leaf axils.  Even after flowering, they still bear the two tiny, curving stigmas that accepted the wind-blown pollen of another tree.  What's more, they take two seasons to mature in red and black oaks, and you can find the larger, older acorns on last year's twigs.

Flowering male catkins of black oak (Quercus velutina);

tiny, bud-like, reddish first-year, and larger second-year acorns.

I've learned that even closely-related trees can vary a lot: red maples are male or female, but silver maple trees have both male and female flowers.  Norway maples trees have male and female flowers, and also flowers will both male and female parts, AND alone of the local maples are pollinated by insects, rather than wind.

 

Female silver maple (Acer sacharinum) flowers

 Male and female red maple (Acer rubrum) flowers.

Unisexual and bisexual flowers of Norway maple (Acer platanoides).

I've caught on to patterns, and to differences in patterns, and become curious:

How does Norway maple come to be insect pollinated, when the other four maples I know are all wind pollinated?  They are very different strategies: insects must be attracted, and the pollen is usually stickier, while wind-blown pollen must be loose so the wind can carry individual grains.

While the other maples drop their samaras gradually over a period of weeks, how is it that red maple drops theirs almost all at once?  Since the seeds are dispersed by wind, it would seem wiser to drop them gradually, in hopes that at least some of the kids would catch a favorable wind.

 Red maple samaras: here today, gone tomorrow.

How can it be adaptive for red and black oaks to take a year-and-a-half to mature their acorns, while white oak does the job in less than one?  A two-year maturation seems riskier to me.

How is it that I could find almost no neighborhood white pine with cones last year, but all those same trees are laden with cones this year? (Yet walking up Great Blue Hill, only ten miles away, revealed  almost none this year.)  Is it rainfall at a critical period?  Temperature?  Wind to carry the pollen?  What??

It's going to be a good year for white pine (Pinus strobus) reproduction.

How is it that red maple, which has its pairs of buds spaced only an inch or so apart--all of which break every spring to produce shoots--end up making such widely-spaced branches?

Tiny "spur branches" may grow only a fraction of an inch each year.
Few will grow into full-sized branches on this red maple.

(I've begun to answer this last: though all buds produce shoots, most of the side buds--instead of growing long shoots the way the end buds do--become very short, small "spur branches" that have leaves packed close together but seldom grow into full-sized branches.) 

I've had to revise my "knowledge"so often that I've learned a good deal of humility along the way.  At the same time that I know more, I'm simply not as sure of myself as once I was.  Part of that, of course, is being reminded of how much I don't know, because I never before thought to ask the questions I do now.

My oldest son is very fond of computer games, and was regaling me a few days ago with news of the new "world" of an internet game: it would have bazillions of stars and planets to explore and gazillions of places on those worlds, so that it would take a single player many lifetimes to explore them all.  

I inquired gently how such places were created.  It seems that some come from the imaginations of game designers, and probably most are computer-generated following some sort of algorithms.  I wondered aloud what the value of exploring someone else's (or something else's) imagined world.  I wondered whether this world had much basis in reality; for example, mountains on earth are usually where they are for reasons of plate tectonics, and their details are matters of rock types and structure, time and climate.  I wondered what the game designers knew about these things.  I concluded that, for my part, I would much rather explore the real thing: actual physical places and things that had evolved over thousands of millions of years of history.  I'm not sure if I got through to him, though.  High definition graphics, explosions, death and destruction are pretty powerful attractions.

The blade of grass you tread on this morning--no less than the greatest redwood--has become fitted by natural selection over millenia to be adapted to a place in the economy of nature.*  That place is a cooperative venture of the species with which it interacts, and a geology evolved over thousands of millenia.  That blade of grass powers its life with light from a medium-sized, middle-aged star a hundred million kilometers away that has blazed for four-and-a-half billion years. 

Computer games?  I still prefer the real.

Our inventions are wont to be pretty toys, which distract our attention from serious things. They are but improved means to an unimproved end.    
Henry David Thoreau, Walden


*"Niche" is the more modern expression, but Darwin spoke of "the economy of nature," an evocative term which I love.