The Buckeye Battle Cry revisited

Species name: Aesculus glabra

Common name: Ohio buckeye

Location: Western University campus

I know I've written a blog about the Ohio buckeye before (you can read my previous blog post HERE), but I wanted to blog about it again but with better pictures. And you know what? I'm allowed, because it's my blog :) So there!

The Ohio buckeye is a native species (well, marginally native. Definitely native to the northeastern United States; debatable whether or not it's native to southwestern Ontario) that does very well in full sun to partial shade. It's a medium-to-small tree in this part of Ontario because it's growing in a suboptimal part of its range, but further south into Ohio and Kentucky it can be a medium sized tree (up to 25 meters tall). The roots of these trees can tolerate intense rain and can tolerate temporary flooding, but do best in well-drained soil. There are some clear disadvantages to growing the Ohio buckeye as an ornamental species, and the first should be obvious: the fruit produced. If you're trying to increase the squirrel population, growing buckeyes in your yard is one of the best things you could possibly do. You don't want to come between a hungry squirrel and a buckeye tree! If, however, you have a lawnmower that you appreciate using and not replacing the blade every time you cut the lawn, you might want to reconsider this species. The fruits produced are enormous (in ideal conditions, some are almost the size of baseballs!), and when they split open they release one to three seeds. The seeds are large, hard, and really hurt when they hit you in the head. They do make fantastic ornaments, and are really stunning in flower arrangements. You can also collect the seeds and dry them to make beads, as is popular to do at Ohio State University. I can imagine they would be good for building neck muscles because they're so heavy, although I'm not sure why you would want to build your neck muscles.

Something that is often believed about the buckeye is that it produces inhibitory chemicals from the roots to prevent the growth of other species (called allelopathy) like in Norway maples and, to some extent, black walnuts. Fortunately, this isn't the case. To date there's no evidence that buckeyes produce allelopathic chemicals from their roots. Unfortunately, that doesn't mean that anything will grow under them! The canopy cover of buckeyes is just so dense that even shade-tolerant grass has a really hard time growing under buckeye trees. The best thing to plant under them would be highly shade tolerant ground cover, but even that might not do it in the long run. But the trade-off? Look at the trees! They're spectacular in their own right. They also turn bright orange early in the fall (late summer, really), long before other species start to change colour. And who doesn't love a bright orange tree in a sea of green?!

So how did the buckeye get to be so closely associated with Ohio? Well, there's the obvious reason that Ohio is the middle of the range for the buckeye, but that in its own right rarely causes a plant to be so ingrained in a state's culture. The story goes that Colonel Ebenezer Sproat arrived in what is now the United States in 1788 to command the Northwest Territory. Once he landed, the Indigenous peoples called Colonel Sproat "Hetuck" because they were so greatly impressed by him; he showed the native people immense respect and communicated with them instead of at them (as so many others did, and, to some extent, continue to do). To Indigenous North Americans, hetuck means the "eye of the buck" which shows power, respect and knowledge. I guess being called the eye of the buck is a great honour! He eventually became known as the "Big Buckeye" and all of the citizens under his control were his buckeyes. Eventually it became a term associated with all of those from and living in Ohio. The common name of the buckeye also stems from the fact that the seeds (or the "nuts") of the tree also resemble the eyes of deer. I bet you'll never look at a buckeye seed the same way again!

Should you decide to try to grow your own buckeye, make sure you find some nice plump seeds before they fall out of the fruit. They are very, very sensitive to drying and won't germinate if the seeds dry out too much. The best way to get around this is to find a fruit that has split open but has not yet dropped the seeds and take them home and put right in the ground. They won't germinate until the next spring, but there's usually a pretty good success rate. Plant a few, then pull all but a couple out of the ground in the summer. At the end of the next summer, choose your favourite and pull all of them but that one out (or leave a bunch! Nothing wrong with wanting a few buckeyes). Just keep in mind that you can't grow these indoors before transplanting (at least, not easily); they do require a period of exposure to extreme cold during the winter in order to germinate properly in the spring. Oh, and invest in a good rake ;)

The dogwood with sandpaper leaves

Species name: Cornus drummondii

Common name: roughleaved dogwood

Location: Western University campus

The roughleaved dogwood is a relatively rare species native to the midwestern plains in the United States. It's nearly native to Ontario, but stops just short at the border in Michigan (some would argue it's native to the southernmost areas near Windsor and Point Pelee in Ontario but no evidence suggests it exists there as a wild species). It is an understory species in the forest, but because it prefers full sun it is most likely to be found on forest edges. Because of the ever decreasing amounts of forest cover, this species is more and more difficult to find.

Unfortunately, I managed to catch this small tree (or large shrub) in what is probably the least exciting portion of its yearly cycle. In the spring and into the early summer it produces dainty white flowers on the bright red inflorescence branches. These flowers are pollinated, then mature into green fruits in the late summer (as illustrated above) and turn white in the fall. These white fruits are important food sources for many native species, including about 20 species of bird, and other small mammals like chipmunks, voles and mice (squirrels rarely eat the berries since they prefer hard-shelled nuts like acorns, but if they're hungry they'll eat just about anything). There are also many insect species that lay their eggs on the branches and leaves of this plant and the larvae ("caterpillars") eat the leaves before moulting into their mature forms. Because of the dense leaf cover and the dense branching growth, this species makes an ideal tree or shrub species for birds to seek shelter. It is relatively fast-growing and then growth is nearly halted when it reaches 4-6 feet in diameter, so makes an ideal candidate for a shrub hedge or other type of visual or noise screen.

Unlike its close relative the red osier dogwood (which you can read all about HERE), this small tree doesn't have much winter interest. The bright red inflorescence stalks that hold onto the white berries turn brown and fall off the tree when the leaves are shed in the fall, and they are produced anew in the spring. The rest of the branches on the tree are a typical brown, unlike the red osier dogwood's bright red bark. This doesn't mean you shouldn't plant one! Think about how happy you'd make some birds if you had one in your back yard :) Aside from the ecological benefit to birds and insects, this tree is incredibly resistant to just about every type of disease out there. It resists nearly all types of fungal infections, there are no known insect pests, and rabbits aren't big fans of eating the bark of this species during the winter (unlike hemlocks. The poor trees in our back yard get stripped of their bark during bad winters!).

The roughleaved dogwood is named that because of the very coarse hairs produced on the undersides of the leaves (the terminal branchlets are also covered in this coarse hair, as are the petioles of each leaf). Because the trichomes are short and fat, they give a very rough texture to the underside of the leaf (almost like sandpaper), unlike the long thin trichomes of many leaves that make them soft and pleasant to touch.

Hackberries can be nature's lightning rods

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!

Snowdrops sometimes turn into trees?

Species name: Halesia carolina (=? Halesia parviflora)

Common name: snowdrop tree, little silverbells

Location: Western University campus

To say that this plant has "a bit" of confusion surrounding the proper Latin name would be an understatement. There isn't just a bit of confusion, there's a whole lot of confusion. Linnaeus (the grandfather of modern taxonomy) was the one that first described this species, and even he admitted later that based on his "vague" description of the species he might not recognize it if face-to-face with it again. I guess that doesn't say much; some of the first biologists interested in assigning proper names to every living thing on earth often gave two, three, sometimes even four separate names to the same organism after forgetting they had already described it and with no Google Images to make the task easier, I don't blame them!

When the original description of a species is somewhat vague and someone else comes along later describing that species and assigning a new name, sometimes this new name becomes the official name. This happened for a while with this species, when Andre Michaux came along and not only provided a much more eloquent description of the species which contained more information, but also deposited a "voucher specimen" (or a portion of dried plant material kept in a dried and pressed plant library called a herbarium) that was much more informative than Linnaeus' specimen. In order for a specimen to be deemed "valuable" or "informative" to a herbarium and to future researchers, you need to be able to see a few key characteristics: either intact flowers or fruit but preferably both, both the front and the back of the leaves, an intact branch or portion of the branch showing the leaf arrangement on the branch, and any other important characteristics of the plant that could be used to distinguish species. If you just press a leaf or two and call it a new species, all green glossy leaves start to look the same after a while! The fact that Michaux's specimen contained both the fruit (of the previous year, which don't dislodge from the branch until the end of the flowering period the next spring) and the flowers as well as some leaves means it was much more valuable than half a fruit and four leaves. BUT. Life as a taxonomist isn't always that easy, especially if you're trying to "one-up" Linnaeus. Most taxonomists today concede that Linnaeus' description and specimen are "good enough" and so his name takes precedence (also because it is older). Regardless of the proper Latin name for this species, the status of the species and the native range doesn't change. The native range has now become highly fragmented due to the urban expansion of large cities; the snowdrop tree used to occupy a large range from Mississippi all the way southeast to Florida and northeast to North Carolina in the United States, but now only occupies a few small pockets in this area where intact forests remain. It is now widely planted around the world as a small ornamental tree, but this doesn't help the regeneration of the natural population. Given more deforestation (due to continued urban expansion or natural disasters like Hurricane Katrina), this tree species will almost certainly be at risk of extinction.

So what's so special about this tree? Well...it's pretty. And that's about all I've got. It's not a particularly outstanding tree for ornamental value, although it does have pretty white flowers (that don't usually have a very strong scent) in the early spring before the leaves emerge, then the unusual four-sided fruits that contain the seeds in the late summer through to the next spring. It's not a particularly good food source for any native Canadian animals since they don't recognize the fruits as being edible (that is, if they're edible at all; a single website states the fruits are edible and taste like cucumbers when still green but I don't recommend you experiment). The tree is incredibly slow-growing and rarely is taller than 10 meters in height. The tree often starts branching very close to the ground, giving it a bushy appearance, meaning the wood is also less than desirable for lumber purposes. The wood can often take on a very "knotty" appearance when grown in the presence of cicadas; they tap into the tree for the sap during the late summer (they use the tree's sap an energy source to make that buzzing sound). The tree goes a bit crazy trying to repair the "tap wounds" from the cicadas, and you end up with giant bulbs of woody tissue protruding off the main trunk and large main branches. Here in Canada the same thing happens, but often as a result of damage by other insects (which is strange, because we also have cicadas. Maybe they don't know they should be drinking snowdrop tree sap in Canada?). These protrusions make the tree look especially creepy at night because of the strange shadows the limbs cast.

Apparently this tree not only has an incredibly showy display in the spring with the flowers (which I'm ashamed to say I've never noticed despite this tree being right outside the building I work in), it also has a spectacular fall colour display. The leaves turn almost a neon yellow, which makes it stand out from all other yellow-turning trees before losing its leaves to overwinter. If I manage to catch the tree before it goes from "green to dead" (as I suspect many trees will this year with our first frost that we had last night...), I'll post an update with the fall colour and (if I remember this long down the road) another update in the spring when the tree is full of flowers.

The common name of this tree, for once, is actually something I can get behind. If you're familiar with early-flowering wildflowers, you will probably know and love snowdrops, sometimes called silver bells. If you've ever looked at them closely, they look an awful lot like the flowers on this tree except smaller and a clear difference between the petals and the sepals (sepals stick straight outwards, and the petals point down towards the ground). If you've never seen this tree before but have seen snowdrops, it will look a bit like you've picked a bunch of snowdrops and crazy-glued them to the branches of the tree to give it some colour. "Snowdrop tree" is indeed exactly what it looks like!

The last of the palms: Otto von Bismarck's tree

Species name: Bismarckia nobilis

Common name: Bismarck palm

Location: Dominican Republic

Well, we have finally come to the end of my images from Dominican Republic, and this is my last plant species to profile from my lovely vacation in February (I can't believe these pictures have lasted me until May! I need to go on vacation more often...). I figured since it's the last one, I should probably go out with a bang...

The Bismarck palm is native to, like almost all palm species, Madagascar and is declining in numbers there (like many, if not most, of their endemic plant species). The fertile land is being cleared and converted to agriculture, with a few select trees being saved to represent landmark "specimen trees" throughout the landscape. Bismarck palms can be incredibly long-lived, have enormous canopies if given enough space, and provide great shade and habitat for other species. By leaving even just a few Bismarck palms, Madagascar is potentially saving tens of species who use these trees as refuge. Unfortunately, agricultural crops are worth far more money to the economy of Madagascar, and these trees likely don't stand a chance of sticking around for long. It's a shame; a country that was once one of the most biodiverse locations in the world is now becoming a barren agricultural landscape. I know I've poo-poo'd on Madagascar in a few blog posts, but the more people know about their biodiversity crisis the more that can be done about it. World economies really need to start putting pressure on countries that house the most diversity to stop cutting down forests because the species themselves have some sort of economic value. It's a slippery slope once you put a price on diversity, but it's true what they say in the business and commerce world: Money talks. Fortunately for the worldwide population of Bismarck palms, they are planted in huge numbers around the world as ornamental species (in the tropics and sub-tropics; they can actually survive temperatures as low as -6 degrees Celsius for short amounts of time). There are two main varieties of this tree: the green kind that's pictured above, and a variety that is almost blue because of a very thick layer of wax that is deposited on the outside of all of the leaves (which you might guess would be much more tolerant of drought and cold snaps; you would be correct with that assumption).

Bismarck palms are some of the most easily recognizable palm trees in the entire world...once you know what you're looking for. They have characteristic fan-shaped fronds with a very thick petiole connecting the leaves to the trunk of the tree. These petioles, as you can see from the image with the pink arrow, are curved presumably to allow the fronds to sway from side to side but prevent the snapping of the fronds if shaken up and down (since we all remember from elementary school that an arch is much stronger than a straight line...right?). This also provides a really unique habitat for animals, other plant species, fungi, and even bacteria since all of the rain that the fronds catch is funnelled down the petiole towards the trunk of the tree. Because the bases of these petioles are so warm and moist, they usually rot right off the tree before the leaf has a chance of dying, especially in very warm, wet areas. The inflorescences produced are also quite characteristic, and look a bit like marine ropes emerging from the base of a leaf. These mature into flowers (some male flowers are pictured in the 8th image; you can tell because they are full of stamens and very little of anything else), which either produce pollen or ovules. These trees, like the pacaya palm (which you can read all about HERE), are dioecious meaning one plant either produces male or female flowers but never both. The trees with the female flowers end up producing the fruit, which starts off green when immature and ripens to be yellow or brown (you can see the green fruit in the bottom image). The fruit are not reported to be edible by humans, although I'm sure someone somewhere has tried them. These are the preferred fruit of some birds and other animal species, so these trees do play an integral role in the food webs of the ecosystems they're living in.

I keep mentioning that these trees are integral parts of their ecosystems, so I think it's about time to show you what I mean. In the two pictures below (the same image, the first one is unaltered and the second one has a bunch of boxes around interesting features) you can see symbiotic plants and animals all living in the same tree:

The green and yellow boxes show the fruit of the Bismarck tree: the green box shows the immature green fruit and the yellow box shows the more mature yellow and brown fruit. Inside the pink box are three different species of plants, the heart-shaped leaf vine, the oval-shaped weedy plant, and the roundish-shaped weedy plant. What these species of plants are I have no idea; they were about 15 meters in the air and I wasn't about to climb the tree to find out! There are also a whole lot of sticks at the top of the tree, which is weird (in the purple box). In fact, I'm guessing that's the way those three plant species managed to make it up into the top of that lone tree; there are no trailing stems or roots to suggest that they "climbed" up there. In the orange box we have a lone bird, who seems to just be hanging out on an old petiole of a leaf. But is he really?

Well, Mr. Bird there isn't actually just hanging out on a petiole by chance; he's protecting his nest. Yes, that massive thicket of twigs was more than likely made by that ridiculously tiny bird (you probably are aware of the species; we call them "that brown bird that makes all the noise at 5 am during the spring" and this common name probably reflects about 500 species of bird). In fact, we stood under the tree for a while and watched more than one of these little brown birds fly to and from the nest; there's likely a whole family of them living up there. In hindsight, it was probably pretty stupid standing under the tree staring up at them (not that I'm afraid of a tiny brown bird or anything): if you're really observant you'll see white patches all over the underside of the palm fronds. Those aren't patches of fungi. Those are patches of "bird paint."

Here's another example of plant species that exploit this tree. Again, I have no idea what species this is since they're just tiny seedlings, but these are growing from seeds that would have been blown down those arc-shaped petioles and landed at the base of the leaf where there is likely an accumulation of organic material that is damp and warm: perfect conditions for plants (amongst other things) to germinate. These plants likely won't last long being squished into a petiole like that, but depending on what species they are they might be able to complete their entire life cycle without ever leaving the protection of their host plant. If those are species that are perennials or require much more space to grow, they'll likely die before producing anything substantial.

And, like I promised in my first blog post about pictures of plants I took while in the Dominican Republic, lizards also call this tree home. These pictures represent what is likely two different species of anole lizard (Anolis spp.) that are in all likelihood native to Dominican. If you think about it, these trees are absolutely perfect habitat for lizards to hide from predators in the petiole hollows, build nests at the bases of petioles, and jump from leaf to leaf to catch bugs to eat. They were pretty curious as to what I was doing holding a camera so close to their home; I guess I did neglect to ask them permission to photograph their treehouse. Next time I'll make sure to bring "lizard waivers" with me!

I hope you've enjoyed the rather long series about "Plants in the Dominican Republic" over the last few months! 

The shedding tropical almond tree

Species name: Terminalia catappa

Common name: Indian almond, tropical almond

Location: Dominican Republic

The tropical almond is a very large tree, reaching heights up to 35 meters tall, native to the warm tropical regions in Asia, Africa and Australia. This particular species (that common name applies to 6 or 7 species in the genus; one of the reasons why I'm not a big fan of common names) is native to India and surrounding area, reaching as far east as China and Thailand. It is planted extensively throughout the New World Tropics (the Caribbean Islands, and Central and South America) as an ornamental species. It was discovered that the seeds of the tree are edible once the very tough outer husk is removed from the fruit, and when this husk is added to fermenting sugar cane an amaretto-like beverage can be produced (and hence the name "tropical almond," not just for the appearance of the fruit which are pointed to by the pink arrow in the third photo).

I have seen this tree on every single one of my tropical vacations; I'm pretty sure I've even seen it planted in Florida. Normally to see an ornamental tree or shrub species everywhere isn't uncommon, since if it's pretty in one area it's likely going to be pretty in another area. But to introduce a species that sheds its leaves during the peak tourist season, as well as its fruits that often attack unsuspecting tourists, is just plain silly to me. You've got all of these thousands of species of native trees to tropical North and South America that keep their leaves all year round; why not use one of those?! For the entire week there were people pulling leaves out of the pool, since during the summer months this is a wonderful shade tree and so logically is planted in areas where shade is desirable.

Medicinally, this plant has been very popular in native herbal medicines around the world for a wide range of treatments: it has reported use in India and Suriname for dysentery and diarrhea, and in Taiwan for liver disease. Interestingly, this plant has gotten a lot of press recently because of the reported benefits it might have in fighting cancer. There are some chemicals in the leaves that reportedly act as antioxidants, but there have been no studies that have shown that this plant has any effect on cancer cells, either in the body or in petri dishes (from any species!). Should someone "prescribe" this plant to someone who has cancer or suggest they drink a tea prepared from the leaves it is highly unlikely to result in death, but don't expect it to melt the cancer cells out of the body. So far it's a fake cancer cure at best. It does have some proven health benefits, but only for a very narrow portion of the world's population. In a study that examined bark extract from this tree they noted that it has the ability to kill the plasmodium that causes malaria, even when this plasmodium displays resistance to all (or many) of the drugs we currently use to treat or prevent malaria. This is a very promising result for those who are diagnosed with (and who die from) multi-drug resistant malaria every year.

For those of you who are fish enthusiasts, you have likely been in close contact with this plant and just didn't realize it. The leaves can remove toxins from water, especially heavy metals that might be contaminating the water. They are used to condition water before it is prepared for fish inhabitants in aquaria. Also, it has shown promising activity in preventing the spread of water molds that grow on fish (usually called "Ick"), effectively reducing disease in fish populations. If you've ever purchased a betta fish (sometimes called a "Siamese Fighting Fish" in pet stores), you've likely purchased a fish that was treated with these leaves as preventative measure to ensure it gets to you, the consumer, disease-free.

Holy guacamole!

Species name: Persea americana

Common name: avocado

Location: Dominican Republic

The avocado is not only a popular tree crop but also a popular ornamental plant species. It has huge morphological variation in the shape and colour of the fruit (one of the reasons why I didn't clue in right away that this was an avocado tree) based on the variety grown, and can also either be a dwarf tree (like this one) or can grow up to 20 meters tall. A bit awkward to pick the fruit! The avocado is native to Mexico and prior to the domestication process was actually a purple pear-shaped fruit with yellow-brown flesh. Very different from the purple oval-shaped fruit with green flesh that we get now! I'd say that the avocados we buy in the store now are slightly more pleasing to the eye, although I doubt they taste any different.

Considering how common the product is, this tree took me forever to identify! Part of the reason is because of its very unusual leaves, which are in part a product of something called "phenotypic plasticity": a trait can vary along some sort of morphological continuum given different environmental conditions. This is incredibly useful in most cases, like being able to produce more surface hairs on your leaves when experiencing conditions of drought, which actually reduces the amount of water lost from your leaves. Other traits, like leaf shape, I'm not sure how it would confer some sort of benefit to the plant. But obviously it does, or else the plant wouldn't bother! The type of leaf this tree was producing at the tips of the branches are called cuneate leaves, which are very wide at the tips and gradually taper towards the base of the leaf. This is a relatively uncommon leaf shape, but a plant commonly grown in temperate areas that has this shape of leaf is the flowering magnolia tree. Another interesting characteristic about the avocado is how the seeds are dispersed. They aren't. Probably not all that successful for an avocado tree! Where these trees are growing in forests in the tropics and subtropics, animals may investigate the fruit and carry them off to eat them elsewhere, but that's not how the fruit would have originally been dispersed. The thought for how avocados were once dispersed stems from the idea that way back in geological and evolutionary time, many more megafaunal species roamed the earth in all habitats (think of the wooly mammoths that North America used to have). In Central and South America there were enormous mega-sloths that were probably, along with gomphotheres or elephant-like herbivores, the main dispersal organisms of this and many other large-seeded plants. These animals would have been big enough to eat the avocados whole, passing the seeds intact through their digestive systems and excreting them in their poo. Their intestines would have scoured the outer seed coat and kept them nice and moist, and the animal's excrement would have acted like a pile of natural fertilizer to kick-start the growing process. Next time you eat an avocado, think about how big your stomach would have to be to not notice that you're eating avocado seeds. Those would have been enormous animals!

Avocados are a great example of a product that is becoming more expensive to purchase because of our growing practices. Avocados are "made" to be grown in Mexico: that's where they evolved and that's where they're best adapted for growing. Sure, we CAN grow them in the United States, which is regularly done in California and Florida, but why would we bother? The plant requires deep watering in order to bear fruit, and water is a hot commodity in California, and the right growing conditions are rare in Florida. This drives the cost of avocados up, only because we're trying to grow them in suboptimal conditions. So why don't we just import them from Mexico? Well, we do now. But up until recently this was not allowed because it was believed that all Mexican avocados were infested with type of fruit fly that would completely destroy crops in the southern United States. I wonder why the government wouldn't assume the fly would travel across the border on its own since it could fly, but apparently that wasn't ever a possibility. The border was completely closed to Mexican-grown avocados until almost the year 2000, which was when the US set up a foreign fruit inspection station outside American borders. It's amazing what we're prepared to do for some guacamole! Today, the US and Canada both accept avocados grown in Mexico, Peru, Chile, South Africa, and New Zealand.

Despite these being tasty fruits to humans, you should always be very careful when using avocados in your kitchen if you have house pets of any kind. Avocado skins are deathly toxic to cats and dogs (as are all parts of the plant if you choose to grow it as an indoor species, which many people do), and they don't seem to understand to stay away from it. A good rule of thumb, especially if you have a dog that likes to raid your garbage can and you like making guacamole, is to rub lemon juice all over the skin before you throw it out. Dogs and cats HATE lemon juice, so that will usually get them to stay away. If you use a compost pile and like to compost avocado skins you might want to make sure you have some sort of deterrent around the outside of your compost pile; rabbits, squirrels, horses and cows (if you live on a farm), and birds are all also deathly allergic to avocado skins.