Sugar maple is in bloom, shaking its anthers in the breeze. This species is supposedly wind-pollinated, but looking closely at the male flowers I saw thousands of bees, wasps, beetles, and even a butterfly working at the blooms. I estimated about thirty thousand insects on the tree’s flowers at any one time. Some were gathering pollen, but many had their heads buried in the bells from which the filaments and anthers hung. Could there be nectar or sugary exudate up there? Why else would a spring azure butterfly systematically work its way across the tree’s flowers? I can find no reference to sugary lures in any of the sources that I’ve read. I’d welcome other observations or insights…
In the Western world, Johannes Gutenberg is widely celebrated for his invention of the movable type printing press. Gutenberg’s work certainly produced a major leap in the mechanization of the printing process, but movable type itself was invented four hundred years earlier by Bi Sheng who lived during China’s Northern Song Dynasty, just after the turn of the first millennium. He used both carved wood and fired clay to create his type, which he then temporarily fixed to an iron plate using resin and other glues.
Bi Sheng’s craft lives on in the work of a small number of wood carvers in China. At the IUFRO World Congress, the International Wood Culture Society invited Jianming Zou from the Ninghuan Cultural Center in Fujian Province to demonstrate and exhibit his work.
The translator said that each block is hand-carved from walnut wood. The blocks were certainly hand-carved, but they did not look like walnut; the program notes indicated that pear and jujube are often used.
In moving away (for much of our writing at least) from direct sensory connection to paper, block, and ink, we’ve lost that beautiful congruence of botanical and zoological talents — wood, inks, our minds — and moved to something that makes the community of life harder to sense. Old, fossilized sunlight, turned to plastic, coal, and mining equipment is still “natural,” but those connections are mightily well hidden.
Take my word for it, I stamped my screen with a block of wood right here:
I took a circuitous route to a conference in Salt Lake City. One of my stops was in south-central Utah at Fishlake National Forest, home to a trembling aspen (Populus tremuloides) grove that we 20th Century humans call “Pando” (meaning “I spread” in Latin). The aspen probably has another name for itself. The root system of Pando may be eighty thousand years old, about thirty or forty times as old as Latin.
This aspen grove covers about 44 hectares (108 acres) and is comprised of one “individual.” Through clonal growth, a founder seed has spread, amoeba-like, over the mountainside to create a forest of nearly fifty thousand stems, which look separate, but are in fact a single organism. The grove is reputed to be the heaviest and oldest creature on the planet, although some fungi likely nudge the aspen out of first place.
The story is not quite as simple as I have described, though. Through a few mutations in the clone (for biojargon lovers: somatic mutations) and perhaps a little sex, the spreading tree has managed to diversify its genetics. Like other big aspen clones, Pando also has an extra set of chromosomes (making it “triploid” instead of the usual “diploid”), all strategies that may have allowed it to defy one of ecology’s more rigorous rules: huge genetically uniform clones don’t last long in the face of environmental stress and disease (e.g., monocultures of agricultural clones are helped along by pesticides and herbicides; if left alone, they’d be eaten alive by fungi, viruses, and bacteria).
When this tree germinated, modern humans were found only in Africa (or so many think, our travel dates are hazy). The last ice age was just getting going. Now, though, the world is truly changed. Heavy grazing by cattle on National Forest land mows new sprouts (cows and their dung pats are everywhere); deer are also abundant. Humans have changed the rhythms of fire and animals. So, the old feller (yes, he’s a male clone), is now in a zoo-like exclosure fence and land managers are encouraging new sprouts to grow by cutting older trees. A flush of new growth has emerged from one of these zones.
He-whose-name-we-do-not-know is being taken firmly in hand, gardened and managed, by the recently-arrived primates from Africa. Check back in 80,000 years to see who is still around.
You can hear them from twelve feet away. Rhythmic grating sounds from within a dead white pine tree in our neighbor’s yard. Sarah heard them first on her early morning walk. We returned later in the day, but the munchers had fallen silent. It seems that their appetite is keenest at dawn.
Here are the sounds, with a labeled spectrogram of the same sound. I suspect that the crunching sounds are coming from large Cerambycid larvae (long-horned beetles). The hairy woodpecker that was diligently extracting them from under the bark would know for sure. Beetle larvae that live under bark can thrive on seemingly indigestible wood using a combination of detoxifying enzymes produced by their own guts and through use of cellulose-digesting enzymes that the insects derive from the fungi that live inside the wood. This is a bit like digesting moldy cornflakes by harnessing the power of the mold. A clever strategy, but one that I’ll leave to the beetles.
Spectrogram (time moves left to right; frequency (pitch) is on the vertical axis):
A maple leaf is more than it appears to be. Its substance is made not just from plant cells, but from a community of many species. “Maple” is in fact part plant, part fungus, part bacteria. Just as the human body is comprised of a vast “microbiome,” plants are also composite creatures.
To get a glimpse at this diversity, I cultured some of the fungal species found on and within the maple leaves growing on the tree by the front door.
To look at the fungi on the leaves’ surfaces, I dabbed maple leaves onto pertri dishes containing agar and fungus food, then waited a few days. Here is one such dish, displaying the diversity of species found on the leaf. Of course, many fungi don’t like petri dishes, so what we see below is a mere fraction of what is actually present on the leaf. The leaf itself is not so thickly coated; the petri dish gives fungi a place to grow and reveal themselves to our eyes.
These fungi from the surface are a mixed bag. Some are potentially harmful to the leaf and will ultimately eat the leaf away when it drops in the autumn. Others are likely protective or live as commensal squatters. Some feed on the droppings of caterpillars or the honeydew of aphids. A few might have drifted from the humans, goats, and stacked firewood below.
To peek at fungi that live inside the leaf, “endophytes,” I sliced some leaves into tiny pieces, sterilized their surfaces, then placed them onto petri dishes. Compared to the leaf “prints” taken from the surface, it took a couple of days longer for these endophytic fungi to appear on the dishes, but they too showed quite a diversity of forms. Here are two examples:
How endophytic fungi interact with tree leaves is largely unknown. But one of their roles is protective, secreting substances that deter the growth of pathogenic fungi. For example, endophytes isolated from Douglas maple release a chemical that poisons a variety of nasty plant diseases.
Interestingly, endophytes in sugar maple leavs seem to be more diverse in old growth forests than they are in younger, managed forests, or in urban areas. But these are preliminary findings. We have only the haziest understanding of the ecology of the fungal world hidden within leaf laminae.
Inside each leaf: a whole community. Within the community: hundreds of stories waiting to be heard. One story is clear, though: if we believe that creatures — humans included — live apart from “the other,” we’re deluded.
“Satsuki” bonsai at the National Bonsai Collection in Washington, DC.
These small trees (Rhododendron indicum) are native to Japan and grow just a few feet tall in the wild. They are cultivated for their prolific blooms and tolerance of pruning. They make gorgeous bonsai and the National Arboretum has several in full bloom. If you’re in the DC area, I recommend a visit. The exhibit closes on June 2. Of course, the rest of the bonsai collection is also looking great as the trees enjoy the early summer rains.
The contrast between the quiet, organized art in the collection and the immediate surroundings of the National Arboretum is striking. Large encampments of homeless people crowd below interstate underpasses and the mentally ill shuffle down buckled sidewalks, talking to no-one and everyone.
Beauty and brokenness. A dissonance that seems particularly painful so close to Washington’s power and wealth.
We mammals tend to regard plants as stationary objects, inert beings that form a backdrop for the more exciting lives of those us of driven by heartbeats and nerves. Here’s some data from a twig on the sugar maple in my backyard that might call us to a more expansive view of our botanical cousins. The graph shows how the diameter of a growing twig changes over a week.
This is the pulse of the tree: one heartbeat every twenty four hours. The twig is fattest at dawn, then the twig shrinks as the water-conducting vessels, the xylem “tubes,” get pulled inward by the draw of passing water. Like a straw that collapses inward under the influence of an enthusiastic drinker, the twig shrinks and reaches its narrowest point in the early afternoon when the leaves are hemorrhaging water to the hot, thirsty sunshine. The twig then gradually swells as the sun lowers and darkness comes. The movement is slight, a few hundredths of a millimeter each day.
Note that the graph shows an upward trend. This young green twig is adding wood, growing day by day.
All around us: every twig throbbing with life.
I was in the Washington DC area earlier this week. Luckily, I had a free morning on the day before the mafiosi closed the federal government, so I was able to visit the National Bonsai and Penjing Museum at the National Arboretum.
Bonsai is an interesting art form, a complicated intertwining of human desires and plant physiology. The trees seem both ensnared and exulted. The trees’ caretakers both control the trees and are their servants. Bonsai and Penjing honor natural landscapes and tree growth forms, yet do so in an entirely human context, providing an interesting metaphor for people’s relationships with the broader community of life.
One of the most striking trees is the Yamaki pine, a tree that first entered cultivation in 1625. It was collected from the wild on Miyajima, the “Shrine Island” in Hiroshima Bay, in the southern part of Japan. The tree is a Japanese white pine, Pinus parviflora, a species closely related to the American white pine, Pinus strobus.
The tree outlived the Edo period into which it was born. Worldwide, the human population has increased nearly fifteenfold during the tree’s life. During this time we’ve discovered all kinds of Earth-shaking technologies.
One of these innovations resulted in the atomic bomb, dropped by the U.S. just two miles from the tree’s home in Hiroshima. Thanks to the fortuitous placement of a nearby wall, the tree survived. Decades later the Yamaki family, tenders of the tree for the last five human generations, gave the tree to the country that had bombed their homeland. We cannot presume to understand all the layers of personal meaning in the Yamaki’s gift of this ancient tree. But against the backdrop of what happened at Hiroshima, their actions evince a love of peace and a depth of generosity that are staggering and inspiring.
A few miles down the road from the bonsai, we have the other end of the spectrum of human maturity: bullying and whining from those in power, and a vortex of anger and recrimination swirling out from this epicenter of malign human relationships. If victims of nuclear warfare can extend the hand of friendship, then so too can the rest of us. Among the many messages I hear in this tree, a question: Can I rise above the corrosive emotions and thoughts that well up within? As I drove past the Capitol building, the answer was: Not yet, unfortunately.
For more information about the tree’s story, see the National Bonsai Foundation’s overview.
I lean my face toward the beech branch and set off a Rio Carnival of dancing insects. Each tiny aphid is dwarfed by the white plumes that arch from the rear of its abdomen. They don’t samba, but they do shake their tail-feathers, pulsing in a loosely coordinated dance as they shuffle along the branch. From a distance the massed white has a creepy air, like the heartbeat of a blighted, molded animal; from closer, the aphids look like flecks of possessed, animated candy floss.
It is only the larger aphids that are adorned in this way. Smaller ones are gathered in a crèche where they squirm their pallid bodies over each other, snuggling into the mass as the larger insects walk over them. Under the twig, this mass swells and a light poke from my pencil reveals — it is hard to say what — a blob, a flattened jellybean, an unformed lump of the same pallid insect flesh.
These odd creatures are beech aphids, Grylloprociphilus imbricator, sometimes called “beech blight aphids” (although they are not a fungal blight) or boogie-woogie aphids (although their left hand piano shuffle is not up to par). Their dance is a defensive warning: insects that amble into the colony will be jabbed by the piercing mouthparts of the older aphids. They are too weak to hurt humans or other large animals, but the creepy-looking dance is enough to make most creatures hesitate for a moment. Any mammal or bird that ignores the warning and takes a bite will get a mouthful of tangling wax as the plumes on the insects’ backs break away. I tongued one or two and can report no apparent defensive chemicals, although who knows what my taste buds missed.
The colony is comprised entirely of clones. A foundress — the blob that was so well hidden in the squirming mass — picked this twig weeks ago and started giving birth to little aphids, genetic clones of herself. The young female aphids feed, grow and defend the colony. Later, some of these offspring will mature into winged forms (alates) that disperse and found new colonies, again reproducing asexually. Then in the fall, some males will be produced allowing a little genetic mixing before the winter.
This species is widely distributed and are quite often encountered in yards. Yet details of its life history are, as far as my literature searches can tell me, mostly undescribed: When does the switch to sexual reproduction happen? How does the foundress feed or is she fed by her kids? How and where do they overwinter? How many asexual generations are completed within a year? What kinds of predators and parasites plague the colonies? Some the species’ close kin (other wooly and gall-forming insects in the subfamily Eriosomatinae of the Aphididae) have ant-like life histories, forming solider castes within the colony. Grylloprociphilus seems less specialized, but without detailed life history studies, we can’t say more.
Aphids feed by using their sharp mouthparts to sup on the sweet phloem sap of plants. This sugar-laden juice is poor in protein, so they have to process a lot of sap to get their dinner. The insects discard excess sugar, coating the leaves and ground below the colony with sticky “honeydew.” This makes the colony quite a hub of activity. As I watched, at least four species of hover fly and one species of fruit fly visited the leaves to feed on the sweetness. And a fungus species, Scorias spongiosa, specializes on the honeydew of the beech aphid, growing nowhere else.
So as the carnival passes, candy gets thrown to the crowd.
I’ve just returned from a short trip to northwest Ontario where I listened to some trees and rocks (a purpose that did little to impress when recounted to immigration officials).
Among the boreal delights were ravens, a species that according to the Objibwe, the First Nations people of the region, brought the world into being and gave the two mainstays of life: water and fish. In the presence of these highly social, intelligent, garrulous birds it is obvious why the Objibwe regard ravens with such respect. Awesome creatures.
A fledgling raven sat in the tree above my tent, calling to its sib and two parents. The following recording, made amid a haze of mosquitoes, captures some of the birds’ vocalizations. The loud, insistent squawk is the youngster. The Objibwe name for raven is gaagaagi and young ravens are known as gaagaagiins, names that capture the talkative nature of these birds.
And as we listen, insects gather to gather atoms for the regional taxation system. Naked mammals are in the highest tax bracket. Note the backcurved sheath, exposing the penetrating stylet. Her hind legs are twitching in delight.
These cherts (from the Gunflint formation) are 1.88 billion years old and contain the oldest known fossils of any lifeform in North America. Until some Australian and African finds beat the record, they were the oldest known fossils from anywhere: life’s first recorded mark upon the Universe. J. W. Schopf’s 2000 PNAS paper has some great photos of these microscopic cells, our (great)^1,880,000,000-grandparents.
In lieu of interpretative signage at this site of Universal importance, we have ♥KIMI blazed on a fir tree. What is amazing to me is not that someone would put their mark on a tree, but that Kimi or her friend came walking in the boreal forest prepared with a can of pink spraypaint just in case. Gotta love Homo sapiens’ complicated inner world, all jumping out of our nerve cells: those microfossils gave rise to some interesting phenomena.
The lichens grow on, poking fresh new growth from under their pigmented parts. If we knew the growth rate of the lichens, we could date this new Gunflint stratum quite accurately.