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In 1999, Nicola Strickland went on a holiday to the Caribbean island of Tobago, and strolled the beaches looking for shells and corals in the white sand, when she came upon a tree dropping green fruit that looked much like small crabapples.  Strickland had a munch of the sweet-tasting fruit before a burning sensation and extreme tightness in the throat got so bad she could barely swallow.  She’d discovered a manchineel tree, what the Spanish explorers dubbed, arbol de la muerte, the “tree of death”.  My name…


Moxie’s doing it again, one of those topics that sounds boring in passing, like salt or mud.  It is my considered opinion that any topic will provide you with fascination if you simply stare at it long enough.  I mean, there are over 3 trillion with a tango trees in the world; you can’t tell me they’re all boring.  They give us lots of our oxygen, shade to cool our concrete jungles, provide us with fruits and nuts — I mean, we wouldn’t have Nutella if not for trees — provide homes for country critters, plus they can talk to one another, albeit with a little help. 


All trees all over the world form a symbiotic association with below-ground fungi.  The fungi send tiny threads called mycelium through the soil.  The mycelium picks up nutrients and water, brings them back to the plant, and exchanges the nutrients and water for a sugar or other substance made by photosynthesis from the plant.  Ultimately, together, both can thrive when they otherwise wouldn’t.  The mycelium effectively increases the surface area of the root system by a great degree, somewhere between a lot and very.  It also creates a network that connects one tree root system to another tree root system, so they can share nutrients and water, a sort of wood wide web. [sfx rimshot boos] Meh, I’m working.  The word for the mutually-beneficial relationships that plants have in which the fungi colonize the roots of plants is “mycorrhiza” describes.  If you’re participating in an adult spelling bee anytime soon, that’s m-y-c-o-r-r-h-i-z-a-e.  


While researching her doctoral thesis some 20+ years ago, ecologist Suzanne Simard discovered that trees communicate their needs and send each other nutrients.  To test her hypothesis, she and her colleagues infused trees with a traceable, radioactive form of carbon,

and later took samples from neighboring trees.  Those neighbors had the radioactive carbon, too, proving that plants could send nutrients back and forth to one another.  Plants need sunlight to photosynthesize, turning carbon dioxide and water into sugar, aka energy, and oxygen.  Simard found that trees in the shade, where photosynthesis is hard to pull off, actually got more of the radioactive carbon than their sunnier siblings.  So the plants know who needs what.  Since then she has pioneered further research into how trees converse, including how these fungal filigrees help trees send warning signals about environmental change.  


The first few “talking tree” papers quickly were shot down.  Talking trees, you can see how that’s a high bar to clear with people.  Statistically flawed, other scientists said, or too artificial, or irrelevant.  Research ground to a halt, …but the science of plant communication is now staging a comeback.  Rigorous, carefully controlled experiments are overcoming those early criticisms with repeated testing in labs, forests and fields.  It’s now well established that when bugs chew  plants’ leaves, they respond by releasing volatile organic compounds into the air.  The establishment of airborne plant patter, conifer convo, and [], put Simard research back on the table.  By last count, 40 out of 48 studies of plant communication confirm that other plants detect these airborne signals and ramp up their production of chemical weapons or other defense mechanisms in response.  Of course, this doesn’t mean that plants have neurons or brains, but trying to tie them to our standards doesn’t do them justice.


A handy place to start podcast research is with superlatives, words that end with -est, e.g. oldest, tallest, thicket and even loneliest.  For examples: The tree with the largest crown, i.e. the spread of its limbs from the main trunk is the “Thimmamma Marrimanu” which is a member of the banyan tree in Anantapur, India.  Its canopy covers 4.721 acres/19,107 m2.  For perspective, the average lot size is the more recent reaches of suburban sprawl is only .25 acres.  This tree’s canopy could shade almost 19 lots!


The highest tree in the world is the rare polylepis tomentella, which grows at elevations of at least 13k ft/4,000m in the central Andean Altiplano, a semi-arid highland area in South America. Despite the dry conditions, these trees can reach more than 700 years in age.  For the lowest tree, let’s look instead at the deepest tree.  My mom always said there’s as much tree below ground as there is above ground.  This superlative belongs to a fig tree in the appropriately named Echo Caves in South Africa.  The tree needs a lot of water so the fruit-bearing part of the tree on the earth’s surface survives and grows deep roots in search of water.  The tree has spent 70 years sending its roots 400 ft/122m deep into the soil, to pump 7 gal/25 liters of water a day.


If you don’t have 70 years to wait, try the paulownia tomentosa of central and western China, the fastest growing tree in the world.  Also called the princess tree or empress tree, they can grow by 1ft/30 cm in 3 weeks and can get as tall as 20ft/6 m in the first year.  I’ve got a red maple in the backyard that’s three years old and it’s still not eye level with me, a scathing indictment if you know how elevationally-challenged I am.  The princess tree also produces *large quantities of oxygen, nearly 3 to 4 times more than other known tree species.  Before you at me on the soc meds about bamboo being faster, so fast that it can be used as an implement of torture, you better come correct because bamboo is a grass.  At the other end of the spectrum, the slowest-growing tree is an individual white cedar on a cliffside in the Canadian Great Lakes region.  It’s managed to grow to an impressively unimpressive height of 10.2 cm, 4 in, and it only took 155 years!  That’s an average growth rate of 0.6mm per year.


That white cedar doesn’t have a ton of company, but it’s doing better than the loneliest tree in the world.  For centuries, a lone acacia tree grew in the sea of sand that is the Nigerian Sahara.  For generations of weary travellers, the solitary tree offered a bit of shade, and a critically important reference point.  European military campaigners learned what the Tuarge people had known for generations, and included the tree, dubbed L’Arbre du Ténéré, and included it on maps.  It was the only tree around for 250 miles402km.  It was not only a natural navigation aid, but also as a monument to the resiliency of life.


It’s also a symbol of interdependence and considerate sharing of resources.  Wrote Michel Lesourd in 1939, “How can it still be living in spite of the multitudes of camels which trample at its sides?  How at each azalai [caravan] does not a lost camel eat its leaves and thorns? Why don’t the numerous Touareg leading the salt caravans cut its branches to make fires to brew their tea?”  But no one let their animals eat it or snapped off its branches to make a cuppa.  That was the year a well was dug near the tree, which offered a hint its odds-flipping-off survival.  The tree, only around 10 feet tall, had roots that stretched down more than 100ft/30m to the water table.  It was estimated to be around 300 years old, the sole survivor from an ancient grove that existed when the region was less arid than it is today.


And then, in 1973, it got hit by a drunk driver.  [sfx game show loser music] According to a contemporaneous report, a truck driver, following a roadway that traced the old caravan route, collided with the tree, snapping its trunk.  The only tree for 250 miles in any direction and yer man managed to hit it.  In an instant, one single act of carelessness severed a link to history, so deeply rooted in the desert sand and in the ethos of generations that had come to cherish it.  Not long after, the remains of the tree were relocated to the National Museum of Niger and placed in a mausoleum.  At the spot where L’Arbre du Ténéré had stood, a simple metal sculpture was erected, marking the spot where it had so long stood in solitary watch over the dunes, and where nothing like it will likely ever stand again.


Let’s go for more quantifiables in our quest.  Tallest tree is trickier than it sounds.  The heights of the tallest trees in the world have been the subject of considerable debate and not a small amount of exaggeration.  The more mature measurement methods are routinely rarely reliable.  Modern verified measurements with laser rangefinders have shown that some older tree heights were recorded as as much as 15% more than the real height.  Historical claims of trees growing to 490ft/150 m are now largely disregarded and attributed to human error.  The current record of 380ft/116m is held by a Hyperion redwood, sequoia sempervirens, in Redwood National Park in California.  That’s 35 stories high.  I can’t remember the last time I was in a building with more than 10 stories, let alone 35.


Measuring on the other axis, the world’s thickest tree is at least as impressive.  A Montezuma cypress in Oaxaca, Mexico has a diameter of 38ft/12m across at “breast height.”  That’s even bigger than the Baobab tree in Limpopo, South Africa that had a wine bar inside its trunk, until it sadly split a few years ago.  But there is still the designation of ‘world’s largest.’  What’s largest if it doesn’t mean tallest or fattest?  The largest trees are defined as having the highest volume of wood in a single stem.  That distinction matters when you consider Pando, which we’ll do soon.  Measurement is very complex, particularly if branch volume is to be included as well as the trunk volume, so measurements have only been made for a small number of trees, and generally only for the trunk.  Few attempts have ever been made to include root or leaf volume, because how would you even do that?  The top 13 contenders on the list of world’s largest trees, such as #1 seed 53k cu ft/1500 cu m General Sherman, are Giant sequoias.  To find a tree on the list that’s not in California, you have to go to Aotearoa, that’s the Maori name for New Zealand.  On the north Auckland peninsula is Tāne Mahuta, the last example of an ancient rainforest that once covered the area.  The 18k cu ft/516 cu m giant kauri tree, also called God of the Forest, is named for the Māori god of forests and birds.


If there are question marks among the measurements of dimension, surely measuring age is easier.  That’s a negative, ghost rider.  For scientists, accurately proving the age of any long-lived species is a hard task.  For example, in 2006, scientists found that a clam called Ming was 507 year old, more than 100 years older than they’d thought….by killing it.  Already I suspect you see the flaw in the “standard” method of determining the age of a tree by counting the rings, one ring per year of growth.   The second problem is that this process, known as dendrochronology, only works for certain types of tree that have an annual growth spurt.  Ring counting isn’t a sure death sentence, though.  Arboriculturalists get the info they need with an increment borer, a drill that allows them to take out a core sample to count the rings *without fatally damaging the tree.  It’s like giving a small tissue sample for a biopsy.  I had one done the other year and I have these bizarrely perfectly round scars, just like the trees would.


It’s a delicate art, taking those samples.  In the 1960s, one scientist’s drill broke off inside the bristlecone pine tree he was sampling.  It’s a specialty tool and if you’ve ever had to buy a specialty part, you know it cost a pretty penny.  A forester helpfully cut down the tree to help him recover the lost instrument, whereupon they discovered the bristlecone pine *had been 5000 years old.  D’oh!


A team of researchers in the US keeps a list, called the Old List, of officially dated ancient trees.  They’ve found a sacred fig tree in Sri Lanka that is at least 2,222 years old.  There’s a Patagonian cypress tree in Chile which, at 3,627 years old, is as old as Stonehenge.  A Great Basin bristlecone pine in California’s White Mountains named Methuselah comes in at 4,850 years old.  But the oldest tree on the list, an unnamed bristlecone pine from the same location, has a core suggesting it is 5,067 years old.  Think about that, 5k years.  This specific, individual tree was already full grown when the Ancient Egyptians started building pyramids and mammoths still roamed the northern climates.


There is another complexity with the question of oldest.  Are we counting strictly individuals or clonal organisms, like certain plants or fungal colonies, which are made up of relatively young offshoots, but these are part of a continuously living being.  If you’ll accept clonal organisms, and why not, we’re accepting of different points of view, we need to cast our eye to Sweden and the province of Dalarna.  There we’ll find a spindly spruce that has been cloning itself for 9,550 years.  The tree currently sprouting is much younger, researchers reported in 2008, but it’s genetically identical to the wood below it that dates back 9,550 years, around the time neolithic man decided he was tired of moving house constantly and that it might be keen to settle down, put in a garden, brew a little beer, bake a little bread.  Adding to the Dalarna spruce’s fascination factor, until the 1940’s, it grew as a sprawling bush, but when the warming climate spurred the trunk upward. The latest incarnation of the spruce stands straight and tall, towering well over its surrounding.


But that 9550 years is a pathetic piffle compared to an even older clonal organism in south-central Utah, a quaking aspen colony called Pando, the trembling giant.  Pando is thought to have been shooting up genetically identical trees for around 80,000 years, based on its current size.  Covering about 107 acres, it was estimated in 1992 to weigh more than 13 million lbs.  Unfortunately, according to the U.S. Forest Service,  Pando is dying.  New shoots aren’t coming up to replace the old ones the way it used to, or needs to.  The cause is suspected to be some combination of climate change, drought and insect predation.


Pando is a massive grove of 47,000 genetically identical stems originating from a single underground organism: the roots of a quaking aspen tree.  Weighing 13 million pounds, he’s the world’s largest organism by mass.  Quaking aspens can reproduce by disseminating seeds, but more frequently, they send up sprouts from their roots and form a mass of trees aptly known as a “clone.”It looks like a forest, but it’s actually one tree, ish, one enormous clone.  The name Pando — which is *not a reference to the fly-looking character who loses an arm in the Cantina in Star Wars: A New Hope, the vowels are transposed — is Latin for “I spread.”  It sounds male, ending with an O as it does, which suits the job since the plant is genetically male.  Scientists have been worried about Pando’s health for several decades, putting up fences to try to protect parts of him from nibbling animals.  Pando seems to have lived in harmony with the local wildlife for thousands of years, but in recent years, Rogers and McAvoy write, the balance has shifted. 


“While Pando has likely existed for thousands of years — we have no method of firmly fixing its age — it is now collapsing on our watch,” says Paul Rogers, director of the Western Aspen Alliance and adjunct faculty member in USU’s Wildland Resources Department.  Unlike a normal grove made up of many types of trees, Pando is a single organism — and as such is much more vulnerable to changes in the environment. It has to share all of its resources across its 107 acres, and to stay alive, it has to send up new shoots to gather sunlight and water as old stems die off.  Unfortunately, write the researchers, mule deer think Pando’s new outgrowths are particularly tasty and like the goats I used to farm, the mule deer find and exploit defects in the fence or just jump clear over it.  The fence is 8 feet tall, by the way.  Quadrupeds with cravings may be eating Pando’s new growth, but ultimately human activity is to blame.  Show of hands if you were surprised by that.  


Under a U.S. Forest Service grazing allotment, ranchers are allowed to let their cattle graze at Pando for about two weeks every year, according to the study. Another major problem is the lack of apex predators in the area — in the early 1900s, humans aggressively hunted animals like wolves, mountain lions and grizzly bears, which would naturally keep mule deer in check. Further state wildlife agencies fund themselves in part by issuing hunting licenses, so they are incentivized to keep the deer populations high, so hunters don’t go home empty-handed.


Human interventions, which also includes shrub removal, pruning, and selective burning, have proved insufficient to help Pando’s plight.  Pando was least able to regenerate in the parts that were unprotected by a fence or had fences that deer could get through. The fenced-in, actively regulated parts fared a little better. But overall, Pando is just not regenerating as much as it needs to survive.  As part of the new study, the team also analyzed aerial photographs of Pando taken over the past 72 years. The images drive home the grove’s dire state. In the late 1930s, the crowns of the trees were touching. But over the past 30 to 40 years, gaps begin to appear within the forest, indicating that new trees aren’t cropping up to replace the ones that have died.  “Now it’s all coming apart on our watch,” Rogers said in an interview. “As soon as we started meddling, things started coming off-center.”


As with all the other changes we’ve wrought on this old world around us, all we can do is change our behavior and attempt, however futilely, to clean up the mess we’ve made. It appears that Pando might stand a chance if we can fence it in and actively keep mule deer out, but doing so could require more than we’re willing to spend.  


If you find a tree with a name irksome, you’re about to be severely discomfited.  How about a tree with property rights?  If there’s not enough humidity where you live, you can take a trip to Athens, GA to meet The Tree That Owns Itself.  In the summer of 1890, a white oak tree, also called the Jackson tree, was granted a plot of land 8 feet in radius around it by its owner, William H. Jackson.  


According to the newspaper, “For and in consideration of the great love I bear this tree and the great desire I have for its protection for all time, I convey entire possession of itself and all land within eight feet of the tree on all sides.”


“For all time” didn’t work out quiiiite as well as Jackson had hoped.  The tree was toppled by a windstorm in 1942, but it was only a matter of time before something took it out, as it had been befeebled by time.  Also by this time, the tree had become a local landmark and the community rallied to replace it.  Four years later, the Junior Ladies Garden Club planted a new tree from an acorn of the original Jackson tree.  So it would technically be “Son of the Tree that Owns Itself.”  But does it actually own itself?  The common law of the state of Georgia dictates that any person or thing receiving property must have the legal capacity to accept the delivery of said property and a tree just can’t.  Regardless of the actual legal status, the city of Athens still acknowledges the tree’s rights, and maintains the tree as part of municipal street clean up.  The oak has become a celebrated member of the community, and locals throw tree birthday parties and decorate it for Christmas.  Every Arbor Day, local schools plant seedlings from the tree, and community foresters have propagated dozens more.


That’s some heartwarming shit right there.  Would it be equivalently dramatic, though, if the tree were arrested?  Eight years after the Jackson tree was planted, in 1898, a banyan tree located in Landi Kotal army cantonment area in present-day Pakistan was ‘arrested’ on the orders of a British Army officer.  And it’s still in custody, tied with a chain, probably to ensure that it doesn’t try to escape.  According to the reports in several Pakistani newspapers, the story goes like this: 

Over a hundred years ago, during the high noon of the British Empire, army officer James Squid saw an old banyan tree and thought that it was lurching towards him.  The officer *was intoxicated, allegedlys,  He felt threatened by the tree and asked the mess sergeant to arrest it.  When an officer says, you do.  The mess sergeant followed the officer’s orders and chained the offending tree.  It stands in the same spot with a board hanging on it that reads: “I am under arrest.”


Locals say that the captive tree is a symbol of the draconian British Raj Frontier Crimes Regulation (FCR) laws. The laws were drafted specifically for the purpose of countering Pashtun opposition to the British rule.  People often visit the area just to look at the incarcerated tree.  Landi Kotal, located at the western edge of the Khyber Pass that traditionally marks the entrance to Afghanistan, has witnessed the jostle of multiple empires as they fought for the remote, rich expanses of the Hindukush.  The tree remains chained as a symbol.  One resident told a local paper, “The tree is a constant reminder of injustice and unfair laws.”


And that’s… The manchineel tree literally holds the record for most dangerous tree in the world.  Every single part of it is extremely poisonous and readily lethal.  There have been reports of severe cases of eye inflammation and even temporary blindness caused by the smoke of burning manchineel wood, to say nothing of inhaling it.  The tree produces a thick, milky sap, which oozes out of everything – the bark, the leaves and even the fruit – and can cause severe, burn-like blisters if it comes into contact with the skin.  That sap is water-soluble, so you don’t even want to be standing under a manchineel when it’s raining.  Remember…thanks…