(a version of this blog post first appeared on October 31, 2012)
Species name:Cucurbita maxima Common name:giant pumpkin Location:photo 1 from Veggie Gardening Tips (clickHERE), photo 2 from McShanes Nurseries (clickHERE), and photos 3 to 6 from The Daily Mail (click HERE) The giant pumpkin is actually a completely different species of squash than the regular pumpkin. When young (or more "natural" plants that have not been bred specifically for their oversized fruit), they are a completely different colour than regular pumpkins (almost red) and a very different shape. They are often sold in the grocery store as an edible squash variety, and called many names depending on their general appearance: banana squash, buttercup squash, Jarrahdale pumpkin, Kabocha squash, Lakota squash, Arikara squash, and the Hubbard squash. The giant pumpkin species originated about 4,000 years ago in southern North America (southern Texas and northern Mexico, but also perhaps as far south as Nicaragua) but was transported quite early in human exploration to Europe where species like it were already familiar to them.Cucurbitaas a genus also has a second area of domestication around Burma, and since that was one of the stops on the great spice route, it was one of the groups of species that had been used by Europeans for centuries. Growing giant pumpkins is a bit of an art form. To get a giant pumpkin to turn giant, first you need the correct variety. If you've ever consumed a Hubbard squash, you know how "regular sized" giant pumpkins can be. Once you have the giant fruit producing variety, the plant still won't produce a big enough fruit to enter into any giant pumpkin contests. To ensure that, you have to get crafty: you have to convince the plant that any sugars produced on a branch of the vine can ONLY be stored in the fruit because they have no where else to go. Normally plants can shuttle sugars produced in the leaves to any storage organ in the entire plant using their network of phloem, or sugar-conducting cells. Some plants make tubers underground (potatoes), and some make starchy or sugary fruit above-ground. In order to ensure that your one favourite pumpkin grows to an enormous size, you have to take a razor blade, and veeeeeery carefully cut the phloem off of the stem in a ring. This normally would be absolutely debilitating to a plant, and is called "girdling." A girdled plant cannot recover, and will eventually die. But what it does in the meantime is prevent the plant from conducting the sugars produced in that one branch to any other part of the plant. Instead, the plant just stores all of it in that one branch, in your soon-to-be-gigantic pumpkin. Some people also swear by watering with a sugary solution, but that won't do anything other than encourage microbial growth around the roots. This might be beneficial for a while, but sooner rather than later a detrimental fungus or bacterium will take over and rot the roots. Not a good idea. Ensure that the pumpkin gets enough water (because if you girdled the branch carefully, the xylem or water-conducting cells will remain intact), and sit back and watch your pumpkin grow! Believe it or not, the seeds of the giant pumpkin are reported to have medicinal qualities. Fry the seeds in oil then grind into a powder, mix with sugar, then suspend that in castor oil. Drink it, and if you've got intestinal worms they will be no more. I think by the time you've resorted to drinking castor oil you're in pretty bad shape and would resort to any treatment, but to me this sounds like a disaster waiting to happen. There have been no scientific studies to suggest that this home remedy is remotely successful in the treatment of any human disease. Use at your own risk! Since today is Halloween, I couldn't possibly pass up one of the most awesome uses of giant pumpkins that have nothing to do with carving them into jack-o-lanterns. Giant pumpkin regattas. Yes, you read that right. There are locations that actually grow giant pumpkins to turn into really awkward kayaks, then have races in them while the "pilots" are dressed in ridiculous costumes. There seem to be points awarded for creativity in decorating your "boat," too, since some of them seem to have some rather unusual additions that wouldn't contribute to the aerodynamics of their vessel. Don't believe me? That's why I have pictures.
Species name:Pinus ayacahuite Common name: Mexican white pine, ayacahuite
Location: Western University campus
I have my suspicions about this tree, and it has nothing to do with the identification. There are three Mexican white pines all planted in a pretty clump; they are definitely ornamental trees and were planted after the arboretum was established on campus (so, believe it or not, these trees are younger than I am. Boy do they grow fast! Because...I'm not that old, no matter what my students would lead you to believe). They are most definitely Mexican white pines. What I have my suspicions about is their distribution and abundance. They are native to three very, very small pockets in Mexico along parts of the mountain range that runs straight through the middle of Mexico. These three pockets are now independent populations, and at the time of their assessment under the IUCN (the International Union on the Conservation of Nature) the three populations were non-interbreeding. This in itself isn't necessarily a big deal, but it's the rest of it that matters. Mexico is undergoing, like many countries in Latin America, a huge shift from rural rolling landscapes where you won't see a person for miles into a highly urbanized country with extensive urban sprawl. On top of that, all of these "Eco Resorts" are popping up all over the country. And then there's the drug running (there's no point in denying that it exists!). Oh, and on top of all of that the conversion from traditional vegeculture multi-crop agriculture to a more "North American" (I hate that description for it, since Mexico is part of North America) method of monoculture agriculture. These four things in combination amount to a lot of deforestation; doing this in an area that already contains three highly fragmented populations of a species, populations that exist nowhere else, probably means that the "Least Concern" status that this species has according to the IUCN is now incorrect. I would bet that at least one of those three populations no longer exists, and that the status of the species should, at minimum, be category NT or "Near Threatened", if not VU or "Vulnerable." But, as with all biodiversity research, you first need to find an organization that will fund the research to go out and study these populations (which hasn't been done since 1994!). To say this is a "Mexican problem," or even a "Third World problem," would be completely incorrect. Under the current economic climate in Canada, the only species reassessments done for species at risk are for species that grow in economically significant areas (like the Tar Sands in Alberta), or in areas where urbanization is slated to occur (in the case of Environmental Assessments). I like to think that Canada is a pretty "developed" country...!
Not having the funding to do diversity studies and study species distributions isn't something that can be restricted to a specific geographic region. It's something we, as human beings inhabiting the world, need to think about. Where are our future medicines going to come from? Nearly 95% of medicines around the world are plant-based or plant-derived (or once plant-derived but now synthesized in the lab). Many of our most successful early cancer treatments originate from plants (taxol is the first one that jumps to mind, and you can read all about the plant that taxol comes from HERE). Our most widely prescribed (and most would argue, for good reason, over-prescribed) antibiotic comes from a fungus (penicillin from the Penicillium fungus). And where would we be without wine (grapes and an alcohol-fermenting fungus) or tequilla (agave and an alcohol-fermenting fungus)?! It would be a sad case indeed. Anyway, onto happier things, like talking about Mexican white pines... :)
The Mexican white pine is one of the most widely planted pulp trees, from which we derive paper. Nearly every large paper-producing country in the world (except Canada) plants the Mexican white pine as opposed to any other white pine species. This is because it is highly disease-resistant (especially to white pine blister rust, which is an ever-increasing problem in Canada and the United States, attacking all of our native white pine species), highly cold-tolerant (despite being from tropical Mexico, it can withstand temperatures of -30 degrees Celsius!), and highly drought-tolerant. This makes it ideal for planting in hot, dry countries, hot, wet countries, cold, dry countries, and cold, wet countries. Name a country that doesn't fall into one of those categories! I dare you :) Because of their large cones, and soft, feathery needles they are also a highly prized ornamental species. One great thing about this tree that makes it ideal to plant as an ornamental is that it doesn't actually get to be that large. The tallest Mexican white pine on record lives in Germany and is only 20 meters tall. That's not a very big tree for being the biggest ever recorded!
Species name: Tilia americana Common name: American basswood, American linden
Location: Western University campus
The American basswood (from now on I'll just call it the basswood, since I'm in one of the Americas) is a great native species that's tolerant of many environmental conditions naturally thrown at it in North America (from Ontario and Quebec all the way south to Nebraska and Tennessee, but some pocket populations even exist in Mexico!). It is highly drought-tolerant, is shade-tolerant, salt-tolerant, and even flood-tolerant. Unfortunately, this tree has largely been replaced in ornamental plantings by the littleleaf linden (or, if you'd like, the European basswood), Tilia cordata, because of the rather unruly growth of the basswood (you can read all about the littleleaf linden HERE).
What do I mean by unruly growth? Well, if you look at the first image that's not exactly the type of "specimen tree" you'd normally see on boulevards. Once this tree reaches a certain height, it's nearly impossible to stop it from starting its bushy growth. It naturally clones from the base of the tree, and suckers form at the base. If you catch them early they're easily removed with a pair of small hedge clippers. But because of their vigorous growth they can get very large very quickly. They can grow so fast, in fact, that it's sometimes difficult to determine which was the original stem and which are the suckers! There are a few varieties of the basswood that don't sucker, but early settlers in North America figured this tree was incredibly similar to the "lime tree" they grew back home, so they just brought their linden trees to North America. Now, you can find large linden trees planted along roadsides as ornamental trees.
If you look at the second and fourth photos, you can see a rather unique characteristic of the basswood that the littleleaf linden doesn't show, and that's that not all leaves are created equal. Since I didn't think to include an object for reference of scale (only realizing after the fact that this was a poor decision), I included scale bars for reference to measure the widths of the leaves. The second image above is of a canopy leaf, as evidenced by the fruit that can be seen growing (they do not grow on sucker shoots until they reach the canopy). The scale bar on that leaf corresponds to about 10 centimetres, or about 4 inches. That's a pretty average size for a leaf in the canopy, but the ones at the very top are slightly smaller (some in shaded areas near the trunk of the tree an also be slightly larger). The fourth picture is a leaf growing on a sucker, and the scale bar on that leaf is about 35 centimetres, or almost 14 inches. That's an absolutely enormous difference, and one that can be consistently seen in all basswood trees (so you don't have to worry that I chose a mutant tree!). So why the huge difference in leaf sizes? This phenomenon can actually be seen in many plants, but to a smaller extent: leaves changing sizes or shapes to be better competitors for light. The small leaves at the very top of the tree don't have to be very big to get lots of sunlight, because nothing is blocking them. In fact, many leaves at the tops of tree canopies are angled so only the edges are exposed directly to this sun which prevents them from getting sunburnt :) (this phenomenon is called "scorch" in plants and is common in plants grown outside of their native range) As you travel further down the trunk towards the ground, there is less and less sun that reaches the lower leaves. They must grow bigger, and are usually darker in colour, to be able to absorb more sunlight to make sugars. For something without a brain, basswoods are pretty smart!
Surprisingly enough, both the leaves and the fruits of this tree are edible to humans, although not all that pleasant. I can't say I've ever tried them, and I also can't say I'll be tempted to do so in the near future. That being said, if you get lost in a maple-beech hardwood forest and are looking for food, finding a basswood would be a nice source of vegetal munchies to sustain you for a few hours. The basswood has also been used as a medicinal plant for many centuries, having effects very similar to the littleleaf linden (which is arguably more potent). The leaves can be steeped in a tea and consumed as a treatment for cough, cold, flu, and indigestion (none of which have been demonstrated to be effective treatments according to modern scientific studies); the flowers can also be steeped for the same purposes but also as a diuretic to promote urine production, as a sedative, and as an antispasmodic to quell intestinal cramps; and even the wood is used (once burned to charcoal) as a treatment for lower leg ulcers, cellulitis, edema, or infection (again, none of these treatments have shown any promise in modern clinical trials). As an aside, rubbing burnt wood into an open wound in order to treat infection is probably not a smart idea. Wood is festering with microbes whether burnt or unburnt (it's amazing the types of bacteria and fungi that can grow on charcoal!), and in order to sterilize it you have to use it while it's hot; rubbing burning wood into an open wound will probably do more harm than good, and I'm sure you can imagine why!
Species name: Celtis occidentalis Common name: common hackberry, northern hackberry
Location: Western University campus
To keep with our "super-massive-gigantosaur" trees on campus, I have a compilation of pictures of the two biggest hackberries. Actually, I might be wrong on that one. When I asked Jane back in June if these were the biggest hackberries, her response was "I think so." Because it wasn't an adamant "yes!," I can't be positive; I'll have to keep track of all of the really big hackberries on my wanderings around campus from now on to see if I can find a bigger one than this one.
Hackberries are trees that are native to the Carolinian forest, with their native range extending from Ontario and Quebec in Canada south to Tennessee in the United States. It still exists in moderate numbers, but has a low tolerance to disturbance so is often one of the first species lost from a forest after a clearcut (even though there are seeds that are still in the seed bank). That being said, they are very good urban trees, and can withstand quite a bit of air pollution with no ill effects. The berries on the tree, which you can see in the third, fourth, fifth and sixth images above, are a great food source for native bird species preparing to migrate south in the fall, as they are some of the most nutritious berries available. They start off green on the tree then mature to a reddish-orange. At this point they can be picked by humans for consumption but be warned: "tart" is an understatement. I tried a bright red berry and thought my mouth was about to turn inside out from the sourness of the fruit! The way that hackberries are traditionally consumed by humans is as a jam or preserve-like substance: the berries are cooked in a simple syrup (equal parts sugar and water) until they are mushy. They can then be used exactly like cranberry sauce on meat! After turning red/orange on the tree they start to turn a dark purple-black, and this is what birds consume. This concentrates many of the sugars in the fruit to make it more energizing, but also concentrates other compounds that react not very nicely with the human digestive system. If eaten raw they can cause severe stomach upset (but nothing that would require a hospital visit unless a whole bucket were to be consumed!). Once they're black and wrinkly like the bottom picture they can be used in wines and beers as a fermentation product. They give the beverage a really fruity undertone that, from what I understand, is unusual and pleasant all at the same time. The good thing about hackberry trees is that the fruit that falls from the tree doesn't start to smell after sitting on your lawn after a while (the same cannot be said for apples, crabapples, cherries, Cornelian cherries, or plums!), and the spent fruit do not attract bees or wasps in large abundance. These trees do grow relatively quickly, so are a great possibility for a boulevard tree. The bark is also spectacular, and one of the characteristics of hackberries that can be used for proper identification even in the dead of winter. In very mature specimens where the bark is starting to peel off, you can soak the bark in water to plump it back up and carve cork-like plugs out of it to use as stoppers. A multi-function tree!
So how big is this tree? Well, it's pretty big. Not as large as the Burr oak from my last blog (which you can read HERE), but still pretty darn large. Here's the herbarium tag for reference:
If we use our same method of size estimation as last time, that tag is approximately 6 x 14 cm (or 2.5 x 5.5 inches). Using my "tag estimation method" (there are about 12 tags that could fit across the tree, so the diameter would be approximately 66 inches or 167.5 cm), the circumference of that tree is 207 inches (5.26 meters)! That's one big tree. But wait...didn't I say it wasn't as large as the Burr oak? Circumference-wise, it's definitely larger at the largest point. But what you'll see if you look closely at the shape of the tree, versus the shape of the big Burr oak, this tree tapers starting nearly at the bottom of the tree. The Burr oak is like a barrel, and only starts to narrow very near the top of the canopy. If you compare weight or total volume of the trunk of the tree, the Burr oak is much, MUCH larger. That being said, this hackberry still has quite a few years left to live (this one is probably "only" about 200 years old) so I'll have to come back to visit this tree every decade or so to see how long it lives and how much bigger it gets!
So what's so special about hackberries? Their berries aren't overly tasty (for humans at least), their wood is of terrible quality (as far as furniture-building goes; it's very brittle and has uneven grain so is only used in cheap fencing and cheap furniture) and isn't very decay-resistant, and they can get old. So far, not very exciting-sounding. Well let me tell you...hackberries can withstand a huge level of "unanticipated stress" and make it out unscathed. Most trees, especially established trees, could never tolerate being split in half and heal up just fine. Hackberries regularly do this. Here's an example:
That tree might not look like much (for size perspective, it's only about half the size of the tree pictured above), but it's a survivor of a really unusual phenomenon, and one that trees rarely recover from like it never happened: lightning strikes. If you click on the image to enlarge it, you'll see a big ridge running from a large wound about 5-10 feet off the ground that extends all the way up to the end of one of the tallest branches. The lightning likely struck the branch, and the electrical charge traveled down the tree until it found a way out; that might have been where a branch once was, or perhaps it was even just a crack in the bark from a burrowing beetle or woodpecker. The ridge, while nearly impossible to tell from the angle of the picture, extends all the way to the ground on the other side of this big hole in the tree. The fact that this tree was nearly split in half by a lightning strike and has since recovered like nothing ever happened is pretty telling to how resilient this species actually is. An absolutely remarkable feat. Makes me want a hackberry just to have it get struck by lightning. What a great story to be able to tell your grandkids, or even great-grandkids!
Species name: Quercus macrocarpa Common name: bur oak (sometimes burr oak or even burl oak), mossycup oak
Location: Western University campus
Burr oak trees (that's how I spell it since that's how I was taught to spell it, but Bur oak is just as common a spelling) are native to the Carolinian forest of eastern North America, and are still present throughout much of their native range. Unlike most oak species, the burr oak does best in open areas like savannahs (depending on the area, they can sometimes be the only oak species in a traditional Oak Savannah habitat) and actually does rather poorly in forested areas. It is very shade-intolerant but grows very quickly, and these two characteristics have made it one of the most popular boulevard trees (or landscaping tree). The burr oak is also incredibly long-lived, with some individuals reaching ages of 350 years or more! That's one old tree!
Like most oak species, the burr oak is known for its masting. Masting is when a tree over-produces fruit in an attempt to overwhelm seed predators so that some of their offspring (fruits are the structures produced by plants to carry and protect their seeds, which are their babies) make it to the next generation. Burr oak seeds are some of the most prized nuts in the eyes of wildlife (like squirrels, deer, and in some places even bears), and they will selectively eat burr oak acorns over any other type of acorn. There are a few reasons why this occurs: first, the acorns are the largest of any oak species ("macrocarpa" means "big fruit"). Second, the acorn wall, or that tough shell you have to crack through to get to the yummy meat of the nut, is quite thin compared to other oak species so it's much easier to eat. Third, there are fewer tannis in the acorns of the burr oak, which make it much more palatable than other oak species. They are rumoured to even be choice edibles to humans, although I've never tried one. As long as you roast it a bit I could see them being at the very least edible, but tasty? I don't know if I'd go that far. I would make a terrible forager! When tree seeds are the most eaten food item of an animal species that has co-evolved with the tree, they tend to use really odd yearly cycles to over-produce fruits. These masting years, depending on the species, are every 7, 9, or 11 years. Our red oak in the front yard had a masting year a couple years ago. It sounded like it was raining acorns every time the wind lightly blew through the tree! It was incredible. The squirrels didn't know what to do with themselves :) To put it into perspective just how many burr oak acorns are eaten by wildlife, there are reports of certain trees in Tennessee and Kentucky in "bear country" near the Great Smokey Mountains having a 0% reproductive rate in some years (non-masting years, that is). When you set up video cameras to check out what's going on with these trees reproducing less than their neighbours, you catch bears climbing the trees and eating every single acorn they encounter. They'll even rip off branches or shake the trunk of the tree to get the ones higher than they can climb (bears are heavy, you know!), and then scramble down the tree to eat what dropped. Something tells me you don't want to come between a burr oak and a bear...
Unfortunately, the burr oak that I took a picture of and its nearest equally old neighbour are on their way out as far as tree lifetimes go. The third picture above shows where a branch broke off many, many years ago and a massive hole has formed in its place. I have no idea if the hole is occupied, but it's large enough to be an ideal place for a Great Horned Owl to build a nest. And those birds are huge! It would also be a good nesting place for a raccoon family, or the equivalent of a Hollywood mansion for a family of squirrels. The fourth picture shows where on that same tree the bark is starting to come off the tree. Unlike in my previous blog post about the butternut (which you can read HERE), this is not a direct result of a fungal infection. There is now likely a fungus that has exploited the tree's old age and exposed wood, but that bark fell off because the tree is just getting old and nearing the end of its natural life. The last picture shows where more bark is coming off the tree near the base, and you can see that it, at one point, was heavily infested with insects. Again, that's likely not what caused the bark to come off in the first place, but once the old rotting wood was exposed the insects took advantage. The tree is also likely hollow, because the old inner wood of trees is often decayed by fungi before the tree is completely dead; this is called heart rot. This also doesn't directly kill the tree, but rather creates a standing hollow tube. Doesn't take much of a wind storm to knock the tree down once the structural integrity is compromised. I personally have no idea how old this tree is (I might be "old" according to my students, but I'm not THAT old!), but I'm guessing upwards of 250 years. It will be a shame to see this tree come down in a storm, and I'm sure it's not that many more years before it does.
Aside from being some of the oldest trees that can be found around southern Ontario and the eastern half of the United States, burr oaks can also be some of the largest. They grow to be very, very tall trees but also grow to an enormous girth. It's hard to tell from the above pictures, but the burr oak I was taking pictures of is one of the largest trees on campus. To put it into perspective, I took a picture of the width of the tree at "breast height" (about 4 feet off the ground; this is traditionally a way to determine if a tree is ready for logging) with the arboretum label for size:
Still doesn't really look like much, but that arboretum label measures 2.5 by 5 inches (or about 6 x 14 centimetres). So if you figure out what the diameter of the tree is (by my rough estimation, 63 inches or 160 centimetres), that's...enormous. That would make it about 196 inches in circumference (or almost 5 meters!). You would need three people joining hands to comfortably circle the tree. That's bigger than enormous! There are two trees of this size that are burr oaks, and a couple hackberries (look for this species to be covered in my next blog), all in the same general location. Standing here looking at the trees, I often wonder what these trees have "seen". They would have survived the entire outwards growth of the city I live in, and would have been here long before London, Ontario actually became a city. I wonder who planted them? Or was this an acorn that sprouted there? If it was, where was the tree it came from? It would be long gone by now. Did anyone care for this tree when it was a wee seedling? If so, who were they? What did they do? Did the Kingsmill family, the ones that owned the property that Western University is built on for many generations before Western purchased all of the land in 1919, ever use this tree for a rope swing? When there were bears living in southwestern Ontario, did bears used to climb this tree to get the acorns? So many questions and no one left to ask...
When I helped Jane Bowles with an arboretum tour back in June, she said that the four trees in this small patch of campus were "some of" the largest, oldest trees on campus. I never thought to ask her where the biggest or the oldest trees were. I guess I'll have to go exploring to find them myself now (and learn a bit about how to determine the age of a really big tree depending on the species). Until then, I'll just have to be content with the geezer trees I know :)
Species name: Juglans cinerea Common name: butternut, white walnut
Location: UWO campus
The butternut is a rather unfortunate tree, and a great example of how "world connectedness" is sometimes a bad thing. The butternut is native to the Carolinian forest, but is now completely absent from North and South Carolina in the United States, and almost completely absent from Ontario in Canada (the two extremes in the natural range of this species). Towards the middle of the range of this species in Ohio, numbers are dwindling quickly. Why is the population of butternut decreasing, you ask? Well, the saying "when in doubt blame it on a fungus" certainly applies here. In fact, when in doubt blame it on two fungi is even more appropriate.
Before we go blaming things on fungi, let's talk a bit about the butternut tree itself. It looks incredibly similar to the black walnut (which you can read all about HERE), but differs in two major ways. The first way that a butternut differs from a black walnut is in the shape of the leaves. Both butternuts and black walnuts have numerous leaflets in their compound leaf (and this number often depends on maturity of the leaf which determines the length of the petiole or the "leaf branch", rather than genetics determining number of leaflets in a compound leaf), but the butternut leaf ends in a terminal leaflet where the black walnut leaf ends in a terminal pair of leaflets. Unfortunately, the wind can shear off the terminal leaflet (pictured in the second image near the pink arrow) so the leaves end up looking identical. So when using leaves to identify species, make sure you look at more than just one! The second way to tell them apart can be seen in the third image above, but admittedly this is a terrible picture of the fruit (the pink arrow points to the fruit in the third image). On this entire tree there was only one single fruit produced this year, so I didn't have much to work with for angles to photograph. But in a nut shell (pun intended), the fruit (or nut) of the black walnut is spherical, but the fruit (or nut) of a butternut is shaped like a football. This can even be distinguished by looking at the shell casings on the ground, so take a poke around the base of the tree if you're trying to identify a butternut or black walnut. Like the black walnut, the meat on the inside of the nut is completely edible, and apparently tastes wonderful when roasted slightly in the oven or pan-fried a bit (I haven't ever had the pleasure of eating a butternut, so I don't speak from experience on this one; see below for why I DON'T recommend eating butternuts).
I guess there's no time like the presence to talk about an evil fungus. The steady decline of butternuts isn't just due to habitat loss (and there is quite a bit of that happening in the Carolinian deciduous forest in Eastern North America!). It's actually because of a disease called Butternut Canker, which is caused by a fungus. :( I know, sad face. But, of course, that's a boring story so I wouldn't just tell you about a single fungus. Recent evidence shows that it's not just one fungus that's responsible for the butternut canker disease, it's actually two. The first one comes in and attacks the tree, causing a localized disease that, theoretically, the tree should be able to overcome. Unfortunately, this causes open wounds in the bark of the tree, exposing the underlying wood and the juicy vascular tissue. This vascular tissue is critical for the survival of the tree, and is the only living part out of all of the wood in the trunk in the tree. Because it is located just under the bark, this is one of the reasons why cracking bark is a critical step in so many fungal infections (sometimes even insect infections or bacterial infections) of trees. Once this vascular tissue has been exposed, the second fungus comes in and completely kills the tree. It will start off being one or two limbs of the tree near the crown (a fancy word for the top), and once the branch loses all of its leaves it won't grow them back the next year. Even pruning these dead branches won't save the tree; once limb death starts it's only a matter of time before the rest of the tree is killed. Because it's a combination of two different fungi that cause the death of the tree, it is exceedingly difficult to come up with a solution to prevent infection. The first fungus that attacks the tree (it has a ridiculously long name: Sirococcus clavigignenti-juglandacearum) is carried by potentially hundreds of different vectors, from the wind to other plant species to insects, and nearly all of these are impossible to prevent from coming in contact with the tree. You might think that lone trees would be most susceptible to this disease, but actually that's not the case. The canopy of the forest traps a lot of pathogens in the circulating air within the forest, so it actually increases the incidence of butternut canker. Lone trees often survive much longer without the disease. This fungus, an invasive fungus introduced from Asia, has managed to infect nearly 90% of all butternut trees left in existence. It won't be long before this species goes extinct, as there is no way of preventing the disease. It's an incredibly unfortunate set of circumstances for butternut trees, and for the Carolinian forest in general. We're about to lose one of the most majestic trees in the deciduous forest of eastern North America. Because this species is so critically endangered, do the world a favour: if you happen to find an intact butternut fruit, don't eat it! Instead, hold it in your hands, do a little "rain and good health to butternuts" dance, and lovingly plant it in the ground. Cover it with some chicken wire (I recommend making a box, and burying it at least 4 inches into the ground over where you planted the seed), and hope for the best. These are one of the preferred food sources for deer and squirrels, so not many seeds manage to escape being eaten (especially considering how few are left). I'm not going to suggest you take a seed home and try to grow it in a pot; that would be illegal in Canada according to our Species At Risk Act (SARA). Even if you plant the seedling back exactly where you found the nut, it would still be against Canadian endangered species laws, and much the same regulations exist in the United States. You might ask who enforces these laws and how common these people are in butternut territory...
Instead of ending on a sour note, let's end on a happy note! There is currently an effort underway in both Canada and the United States to try to protect the butternut in some way from disease. The method developed currently will not save the trees that are dying, but will instead protect the new generation of butternut trees. When butternuts are hybridized with the Asian walnut, the tree has almost complete resistance to the butternut canker. This is great, but unfortunately it dilutes the genetic pool of butternuts with Asian walnut genes. To try to combat this (since hybrids don't actually have any status according to any endangered species act anywhere in the world), hybridizing this hybrid with a different butternut tree causes the tree to have characteristics that are nearly identical to the butternut, but still have the disease resistance of the Asian walnut. This process is known as "back-crossing," and is commonly done with agricultural plant species to introduce disease resistance. This still doesn't make a "true butternut," but the resulting tree is nearly identical to a genetically pure butternut. There might come a day when we have forests containing this "butternut" (technically called a "Butter-Buart" which to me just sounds strange) in abundance once again. I wonder if anyone has tested the edibility of the butternuts of this backcrossed hybrid to determine tastiness... :)
Since today is Thanksgiving Day in Canada, I figured I should post a blog about a plant that is essentially analogous to Thanksgiving in both Canada and the United States (yes, I know your Thanksgiving Day is in November...you weirdos!). That plant, of course, would be the pumpkin. What's Thanksgiving (or Christmas, for that matter) without pumpkin pie?!
Pumpkins are actually a specific variety of the species Curcurbita pepo, one that has been artificially selected for an over-sized fruit and the orange colour (or white, depending on the cultivar). The species Curcurbita pepo is actually one of the most variable and one of the most popular fruit/vegetable species that we currently have in cultivation. We get zucchini, acorn squash, delicata squash, dodi marrow, gern squash, heart of gold squash, pattypan squash, pumpkins, spaghetti squash, sweet dumpling squash, crookneck squash, and summer squash all from that one species alone! It's amazing what human selection for various traits can do to a species. This species is native to North America, but likely native to a region in the north of what is now Mexico, or the southern parts of Texas, New Mexico and Nevada.
Pumpkins are a great example of integrative agriculture, and how agriculture has changed over the centuries. Traditional plantings of pumpkins (or any squash) were not monocultures like you would see today (entire fields of nothing but pumpkins). Native North American people used to grow squash in association with corn and beans, and those three crops are what we now refer to as "the Three Sisters." Corn depletes the soil very quickly of nitrogen because it requires so much to grow, but beans create biologically-available nitrogen through the nitrogen-fixing bacteria in their root nodules. Beans are vines, and require props to grow so they wind themselves up the corn stalks to use them for support. Squash plants are very far spreading plants that cover the ground surface and don't require many nutrients (surprisingly enough), and due to their large leaf size they out-compete weeds for light resources. The three crops grown together create their very own bio-feedback ecosystem, and ideal harvests come from all three of these crops being grown together. Now with fertilizers and pesticides we no longer require the synergistic action of all three crops in one field, but you can see how this concept will become useful once we decide that dumping chemicals on our food is not the ideal way to grow plants. If you'd like to read more about the Three Sisters, you can do so HERE.
Happy Columbus Day to my American readers, Happy Dia de la Raza to my readers in Latin America, Happy Discovery Day in the Bahamas, Happy Dia de la Hispanidad to my readers in Spain, Happy Dia del Respeto a la Diversidad Cultural to my readers in Argentina, and Happy Dia de las Americas to my one lone reader in Uruguay!
I figured today I would do an "ecosystem" blog, since those seem to go over really well. It's not often that I can talk about a whole bunch of plants and how they interact together, since I'm not a true botanist (although, if this was back before 1969, I would be a botanist since fungi were considered part of the plant kingdom...but that's another story for another time). Learning about how plants interact with each other (and sometimes how insects interact with plants; this is coming sometime soon to a blog post near you!) often takes a lot of research, and since I've got enough of my own to do lately with writing a thesis, I've got to keep my priorities straight. But this is an ecosystem I know quite a bit about, since I live there: my back yard. I just took a picture of a tiny piece of my back yard, and figured we would start in one area of the photo and move through it and talk about each plant. So here we go! Pay attention to the numbers in pink to know what's what. Many of these plants I've blogged about before, so if you'd like to learn more about each plant you can click on embedded links that will take you to previous posts.
1. This is the evil periwinkle. We even have both species of periwinkle in our back yard: the "major" species and the "minor" species. If you learn one thing from me about gardening, let it be this: if you're newly landscaping a yard and starting fresh, don't EVER plant periwinkle. I've been trying to get rid of it for months, and every time I seem to make a dent it grows back twice as fast. That's because it actually thrives after being disturbed. As soon as you rip off a piece, the plant recognizes that it has been wounded and immediately shuttles resources to that area of the plant to repair itself and to regrow. Sneaky, sneaky plant. The only way to truly get rid of periwinkle? Burn it. Since I don't really want to set my back yard on fire, I guess I'll have to settle with ripping areas of it out every so often until I weaken it enough to kill it. Periwinkle, one day you're going down. Mark my words. You can read more about periwinkle and one specific species of it HERE.
2. This is a shrub-like ground cover I haven't blogged about before. The species name of this plant is likely Euonymus fortunei, and I have no idea what horticultural variety it is. Like periwinkle, once planted it's darn near impossible to get rid of, and spreads like nobody's business. It doesn't grow very tall off the ground and looks rather boring, so if I had a choice it would be gone.
3. This shrub with maroon leaves is called ninebark. It's a great native species, and gets its common name from the way the bark peels off of the stem (it curls around, appearing as the number "9" when you look at it from the side). It's a relatively uncommon garden plant since it has a rather undesirable quality: it is quite susceptible to both powdery and downy mildew. The last thing you want is for all of your lovely maroon leaves to turn white and fluffy, but the best way to avoid this is not to water your garden using a sprinkler, but rather a soaker hose near the base of the plants. If moisture is on the leaves for a prolonged period, that's when problems arise. If the leaves stay as dry as possible, there's less of a chance of your ninebark being affected. There are some varieties on the market that are more resistant than others, so check which type you buy before you buy it. You can read more about ninebark HERE.
4. This is a hosta, as I'm sure many of you figured out on your own. Hostas are some of the most popular garden plants in North America, since they are so tolerant of many different environmental conditions, and they are so variable in their morphology depending on variety. We have some of the "blue" type of hosta (the leaves are a dark green and are covered in a very thick layer of wax which gives a blueish tinge to the leaves), variegated leaves with white edges and green interior (and the reverse on other plants), variegated leaves with dark green edges and light green interior (and the reverse on other plants), and plain green leaves. I personally find hostas boring. I think there are plenty of other native species that produce much more exciting flowers with better scents than hostas, and they're better for attracting pollinators of all types into the garden. That being said, they're not nearly as terrible as periwinkle, English ivy or Euonymus since they don't spread quickly and don't produce viable seeds (at least, not in Canada they don't). They do spread, and will take over an area if left unchecked so make sure you keep them confined to their space (especially if you live near an Environmentally Significant Area). You can read more about hostas HERE.
5. This is the trunk of our Dawn Redwood, one of my favourite trees. It is called a "living fossil" because it was known from fossilized remains long before it was discovered growing in China. It is still critically endangered in the wild, but population restoration efforts are underway to try to bring this tree back to its former glory (it was once abundant worldwide during the time of the dinosaurs). One of the best things about this tree is the texture of the wood; when the tree is alive and healthy the trunk is almost spongy on the outside. It's also fire-tolerant like many other species of redwood that actually require their seeds to be burned in order for them to germinate. Pretty cool! You can read more about Dawn Redwoods HERE.
6. This small shrub is a horticultural variety of white pine. It grows very slowly, but seems to be much more prone to disease than our white pine trees in our back yard. We used to have three of this type of shrub, but have had to replace one already because it was completely dead. This one has died on one side and has been subjected to some pretty brutal pruning; when shrubs or trees are so slow-growing, it's really bad for their health to prune half of the plant away, even if it's dead. What might look dead to you might not be considered dead to the shrub or tree, and it can often have disastrous consequences. Keep that in mind around this time of year, since the late fall and the early spring are the "seasons for pruning". Fast-growing species won't be bothered with pruning; before you know it you'll probably have a new branch taking up the old one's place. You can read more about white pine trees HERE.
7. This tree that you can barely distinguish in the picture is a European beech tree, and one that seems to be on its own schedule. This year is the "year of the beech mast," and so most beech trees produced an over-abundance of beech nuts in the prickly seed pods that is so characteristic of beech trees. But not this one! Not a single seed in sight. I always knew our beech was "special." :) While not the same tree, you can read all about European beech trees HERE.
8. Even less visible in the photo is the shrub behind the ninebark on the far right, a dogwood. Not just any dogwood, either; it's a red osier or a red-stemmed dogwood. It produces these spectacular white berries in the fall if left untrimmed, and these can be a great food source for birds (depending on the bird, of course). They are a native species, and are popular garden plants because of their very attractive branches which remain bright red all winter. Again, not the same individual shrub, but you can read more about red-stemmed dogwoods HERE.
So that's that! A blog about a tiny little piece of my back yard. Surprisingly, the hostas and ninebarks are tough enough to put up with the periwinkle trying to steal all of their resources, and while not out-competing the periwinkle they seem to be holding their ground. The Dawn Redwood has grown far more than you would expect since we moved in based on the normal growth rate of the tree, so we seem to be doing something right. While the white pine shrub is unhappy, it's been there since day one in the garden so it can't be THAT bad. I'm guessing the same thing killed its branch as killed our white pine tree that was just across the path from it, so it wouldn't surprise me if the whole shrub was dead in a couple of years (beetles. Evil bugs!). The dogwoods always grow to unmanageable sizes during the spring and summer, but the birds love them (we've had a cardinal nest in one of them for the last few years in a row, so they provide great shelter to birds).
BUT WAIT. What if this entire blog was...a ruse? Hopefully the most observant amongst you noticed that this likely wasn't about those eight plants at all. Sure, it's nice to see eight different species in a tiny area of a backyard garden all working together. But actually...there are nine species there. And the ninth is by far the most exciting.
Do you see it?
Zooming in to the base of the ninebark might be helpful. What's that?! Why...mushrooms. The fall is "the season of the fungus" in many areas of the world because it gets so wet from fall rain storms, and the nights cool off which can stimulate some fungi to produce mushrooms. Shaggy manes are some of these fungi that require cool nights in order to produce mushrooms. This is why you find them most often in the spring and in the fall (and rarely during the summer since it is way too warm).
Who knew I would go to so much trouble just to camouflage a mushroom blog?! :)
Species name: Coprinus comatus Common name: shaggy mane, shaggy ink cap
Location: my back yard in London, Ontario
Normally I try to reserve my fungus-related blog posts for Fridays, since that day is officially "Fungus Friday" to my field. But today is an extra-special day, at least to one area of the world. Today, October 13th, is National Fungus Day in the United Kingdom. How awesome is that?! A whole day dedicated to fungi and how awesome (and useful) they are. I think this is a great idea, and Canada really needs to get on this bandwagon. That's one of the unique things about the UK: they're much more in-tune with nature than we are in North America (generalizations; this obviously doesn't apply to everyone in either location), and take a much larger role with public education and why diversity for the sake of diversity is important. This is something that is starting to become more important in Canada, but industrialization of the country is quickly gaining ground on preservation of our natural areas. Whenever there's a significant area of land designated as "green space" (or even worse, "vacant land") it is increasingly likely to be snatched up by a developer, bulldozed, and some kind of new development (mall, apartment building, housing complex, etc.) put in. Having days like a "National Fungus Day" or a "National Tree Day" (or "Earth Day," as we have here in April) is a big step towards educating everyone about the value of diversity and why it needs to be maintained (or even augmented!) in urban areas.
Now onto information about the shaggy mane! This mushroom carries special importance in my life, as I'm sure it does in many mycologists' lives (amateur or professional): this was the first fungus that I learned to identify by Latin name. Shaggy manes will always be near and dear to my heart. It wasn't until a couple of years later (I learned the Latin name of this species in a plant diversity course in my second year of undergrad) in graduate school that I learned that these were edible and that their method of spore dispersal wasn't very special after all. But let's start at the beginning.
As this mushroom develops, it starts off as a little white stub emerging out of the ground. It almost looks a bit like a shaggy egg. This egg will elongate, and eventually the top of mushroom, or the cap, will detach from the base, leaving a ring around the stem (the technical term for this is an annulus, but "ring" works just fine. You can see this in the 5th picture above). This ring is a very fragile piece of fungal tissue and often detaches with age, but if you manage to find an intact ring on the stem of a fungus make note of it (especially if you're trying to identify it later). Rings are sometimes the only way you can tell two species apart (one will have a ring, the other won't). As the stem continues to elongate once the cap has detached from the ring, the gills develop on the inside of the cap. You can see them in the last picture where a squirrel has kindly separated one of these mushrooms in half so you have a clear view of the inside. The gills almost look "fuzzy", and that fine granulation are the spores being produced on the gills. The spores are a brown-black, so the gills get darker the more the spores mature. Here's where what I learned the first time and what I learned the second time about this mushroom's spore dispersal mechanisms conflicts.
In the picture above you can see the bottom edge of the mushroom starting to curl outwards and turn black and goopy (more easily seen in the 3rd picture above). Originally it was thought that this was the way that the mushroom disperses its spores: the mushroom cap auto-digests, leaving this black liquid behind that contains huge masses of spores (you can see this black goo on some of the periwinkle leaves in the above photo). If you think about this idea, it should seem a bit illogical to you (hopefully it does!). The whole point of producing spores is to reproduce. The spores, like seeds produced in the higher plants, are the babies of the mushrooms. Two spores must come into contact (conjugate) in order to produce a new fungal individual (like egg meeting sperm). Like human children, the mushroom prefers if their children "go off and prosper" in the world. How would this happen if you're dripping your babies onto the ground directly underneath you? That would mean that your babies could only start growing directly under you, and because you're a very efficient fungus you've already used up all of the resources there are to use. This obviously isn't optimal for your children; they're being born into a world without food. And no parent wants their child to start off in the world that way (human or otherwise)! Some fungal scientists (mycologists) decided to test this idea by taking some of the black goop and spreading it on petri dishes with nutrient medium. If the goop contains spores, they should start growing. If the goop doesn't contain spores, nothing should happen. Guess what happened? Nothing. No growth, no nothing. The goop really is just the fungus digesting itself because it has no use anymore for the mushroom; they are very "expensive" energy-wise to produce and maintain, so if you don't need it anymore then they're a good thing to get rid of. This is one of the reasons why mushrooms are so short-lived. The bonus of this is that the black goop actually contains quite a few nutrients in it, so the fungus can use its former self as a new food source to keep spreading underground. Pretty crafty! So where do the spores go? They're produced on the gills like any normal fungus, and then they...blow away in the wind, like every other fungus (OK, almost every other fungus). Not a very exciting story after all!
As I mentioned above, these mushrooms are edible, just pick them when they're young. The black goopy stuff isn't toxic, but is quite bitter compared to the rest of the mushroom because all of the sugar is being digested. As these mushrooms are cooked they will turn black and soupy (don't be alarmed; this is normal for this fungus when heated), so a lot of people (me included) are put off by their appearance. From what I hear from multiple sources, they are quite tasty. Maybe I'll finally break down and try them sometime. There has yet to be a single instance of the chemical coprine being isolated from this species (the active chemical in the drug Antabuse; it reacts with alcohol to induce projectile vomiting to try to dissuade alcoholics from drinking), but many people who report having sensitive stomachs may still react to this mushroom, especially when combined with alcohol. If your stomach is easily upset after eating unusual foods, I suggest you consider finding a different mushroom to eat for dinner.
I hope you've enjoyed my "fake-real blog post combination" to celebrate this special day: National Fungus Day. The Royal Botanical Gardens Kew in London, England put together not only a fantastic day in their gardens and in their fungarium (a museum-like place full of dried fungal specimens) to help educate the public about fungi, but also a wonderful art installation throughout the gardens by world-famous sculptor Tom Hare. They have put together a short video about the art installation, and it contains a great narrative by the curator of the fungarium, Bryn Dentinger. It's a GREAT video, and definitely worth a watch! Kew has also put together a "behind the scenes" video of the Kew Fungarium that's also a great way to spend 5 minutes and 35 seconds of your time.
