Wednesday, October 31, 2012

The best boat ever made in nature

Species name: Cucurbita maxima

Common name: giant pumpkin

Location: photo 1 from Veggie Gardening Tips (click HERE), photo 2 from McShanes Nurseries (click HERE), 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. Cucurbita as 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.

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 (this sounds incredibly dangerous...I wouldn't EVER recommend that someone ingest castor oil, for any reason!). 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.

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.

Happy Halloween!

Tuesday, October 30, 2012

The Canadian beer-tree

Species name: Ptelea trifoliata

Common name: hoptree, wafer-ash

Location: Ontario

The common hoptree or wafer-ash (named after the wafer-like fruit that persist on the tree until the following spring) is a rare species in Ontario, but the native range of the species doesn't extend far into Canada. Species become less and less common towards the limits of their range (whether the northern edge or the southern edge) since those habitats are less ideal than towards the centre of their range. There is the potential for this species to become more common as the climate changes, but there doesn't seem to be anywhere for this species to expand northward.

This species belongs to the Rue family, or the citrus family. It is the northernmost species of this family on any continent. When the young twigs or leaves are bruised or ground, they smell distinctly like lemons or oranges. Fantastic! The fruits look similar to the hop fruits normally used to flavour beer, and when used for that purpose the fruit of this species give a similar flavour (and hence the common name). The trees themselves rarely actually look like "trees," as in the first image above. The branching occurs very close to the base of the tree, giving it more of a bush-like appearance. For this reason, it's not a popular ornamental tree species, but would fit very nicely in a location meant for a shrub (but they can grow to be 8 meters tall under the right conditions!). They are not ideal for providing shade, since the branches don't fill out well towards the top of the plant. They're very..."sticky."

Sunday, October 28, 2012

The maple with gold paper bark

Species name: Acer griseum

Common name: paperbark maple

Location: Ontario

This species of tree is native to China, and is used there extensively as an ornamental plant. It has recently taken hold of landscapers' attention in North America (recently as in approximately 60 years ago), and is becoming more and more common here. While being non-native it is incredibly tolerant of cold, harsh Canadian winters and survives well; it reproduces on its own incredibly poorly here and so there is very little chance of it becoming invasive.

The bark of the paperbark maple is very similar to the bark of a birch tree; the outer layers of the bark, instead of being heavily suberized (waterproofed) and hardened onto the tree's surface as scales, are instead gradually sloughed off in almost transparent layers that are only a few cells thick. This gives the tree almost a shimmery appearance under the right light conditions, one of the reasons why this plant is so favoured for its ornamental value. The leaves are also quite spectacular, at least as far as maple leaves go. The leaves are so heavily lobed that the lobes with the main veins actually turn into leaflets like you would see in the Manitoba maple. The main difference between the leaflets of the Manitoba maple and the paperbark maple is that the Manitoba maple shows a huge amount of phenotypic plasticity: the ability for a structure to show very different morphology based on growing condition. The newest leaves only have three leaflets (which sometimes fuse together under unusual circumstances to make one full simple leaf) to as many as nine leaflets in the older leaves. The paperbark maple only has three leaflets per leaf, no matter how old the leaf is.

The leaves of the paperbark maple deserve just as much mention as the bark, since they're quite pretty no matter the season. In the spring when they first start to grow out of the buds they're almost white and furry, then towards the late spring and during the summer the tops of the leaves are a dark green while the undersides are almost a pure white. In the fall, the leaves turn my favourite colour: pink. They almost end up the colour of pink strawberry candy before falling off the tree. It might be a non-native species, but it's certainly one of my favourites!

Saturday, October 27, 2012

Once upon a time Freeman made a maple

Species name: Acer x freemanii

Common name: Freeman maple

Location: Ontario

Technically speaking, the Freeman maple isn't actually a species at all, but rather a hybridization between a red and a silver maple that happens often in nature when the two species are present in the same location (which is often; their native ranges overlap almost completely). Depending on whether it's silver maple pollen or eggs, you can get drastically different phenotypes (or appearances of the tree). I'm betting that this tree was produced as a result of red maple pollen and silver maple ovules (eggs); the characteristics of this tree are almost identical to the silver maple except for the bright red petiole of the leaf. In fact, this tree is labeled as a silver maple on campus, but I have my doubts. If it was truly a silver maple with no hint of a hybrid, it would have green petioles and would be turning a yellow-green in the fall, not red.

So why would you want to hybridize a red and silver maple? Well, the silver maple grows very quickly, and so provides shade to an area faster than a red maple would which is often a desirable outcome of planting a tree. The downside of the silver maple is that their roots can often be quite invasive. They don't grow very deeply into the soil, and can bubble up concrete or asphalt easily which is not always a desired outcome. The red maple has much deeper roots that don't creep along the soil surface, so there is less of a chance of destroying nearby sidewalks, roads or driveways. The wood of the silver maple is also incredibly brittle. Normally this doesn't matter since many people enjoy the tree and not the lumber at the end of the day, but silver maples also have another dirty secret: they're almost always hollow due to heart rot (a fungal disease where the fungus targets the old, dead wood on the inside of the tree that is used for support). This is great for wildlife who require hollow trees to nest, but terrible for your house or garage during a wind storm; trees shown on TV that have crushed cars or houses after a violent storm (not a tornado) are often silver maples. This doesn't happen with red maples. Their wood is much more durable, and they are less likely to get heart rot and so are less likely to be destructive during a bad storm. The last reason why you might want to hybridize the two species is because of the aesthetic factor; bright red petioles are much prettier than just plain old green ones. Depending on the number of generations since the initial hybridization, the leaves might also turn a brilliant yellow-orange during the fall instead of the silver maple's boring yellow-green. You never quite achieve the neon red of the red maple's fall coloration, however.

Thursday, October 25, 2012

The "little sister" pine

Species name: Pinus resinosa

Common name: Red pine, Norway pine

Location: Ontario

Surprisingly enough, the common name of this species is not reflective of its natural heritage. Sure, it's an economically important tree in Norway, but it certainly didn't originate there and more than likely wasn't first discovered there, either. The red pine is native to Canada and the northeastern United States, is the state tree of Minnesota, and is much smaller in almost every respect compared to the eastern white pine.

It is relatively uniform in its morphology, so you'll rarely see "exceptions" to the general shape, size, colour, and rate of maturation of any one member in a population. This would suggest that each member of the population is very genetically similar, and that each copy of each gene has few alleles (and perhaps only one allele expressed in two copies). How does this happen? Well, there's only one way: near extinction. This very concept has happened recently with the cheetah and also the eastern cougar. The populations are so genetically uniform that very strange genetic deformities are starting to appear more and more commonly in the population. In a "pristine" population, one that hadn't gone through a near-extinction event, genetic diseases are rare and you usually need two copies of a gene to express the disease. If you only had one copy, you would appear normal, and no copies you would appear normal and any children you had would also appear normal (since no matter what genes they get from your mate, you will be passing on one of your two normal copies of the gene to your children). Because an individual with one normal copy and one recessive copy appears normal, selection cannot act to "weed" that individual out of the population. If that individual mates with another individual that has one normal copy and one recessive copy of the gene, they have a 1/4 chance of having a child with the disease. The same thing happens in plants, but many plants can be what we call tetraploid; this means they have four copies of each gene instead of only two. You can see how this might be of great advantage in the plant kingdom; in order to show the effects of a recessive gene, you would need to have four copies of the gene instead of just two, which would occur much less commonly.

The presence of a large number of red pine trees in an area is usually indicative of a widespread natural disaster of some kind, usually a forest fire. Because they are incredibly intolerant of shade, they are often the first trees to colonize an area after fire. Contrary to popular belief, this isn't because the seeds require intense heat to open (which is the case in some other coniferous species). When you intensely burn an area it rapidly decomposes the dense organic layer on top of the soil which allows for easier seed penetration, it burns off insects that might eat the seeds or young saplings, it removes the competitive ability of understory trees and shrubs by killing all (or some) of them, and thins out the branches of the trees that make up the canopy. Fires provide optimal growth conditions for the red pine and other primary colonizing species that are shade intolerant.

The uses of the red pine include lumber, pulp and paper, and for landscaping purposes.

Wednesday, October 24, 2012

The rugged rose

Species name: Rosa rugosa

Common name: Japanese rose, wrinkled rose

Location: Ontario

This species of "wild" rose (it is also cultivated and sold in garden stores, so most plants probably aren't truly wild) is incredibly popular across the world for a diverse number of reasons. The native range of this plant is enormous, ranging from western Europe all the way east to Japan and Korea, as far south as Turkey, and as far north as the southern edge of Siberia. It has adapted to a wide range of habitat types, but prefers areas that have moderate levels of disturbance, low nutrient levels in the soil, and full sunlight (for those reasons it does very well on sand dunes and in sandy soil but also roadside ditches). It can often be seen as a garden escape growing in very shrubby areas, where it can dominate (at least for a short time, until buckthorn comes in) the area quickly.

The genes determining flower colour in this plant are very similar to each other. What I mean by that, is that for every single gene in our genome, we have two copies of that gene. One we inherited from our mother, and one we inherited from our father. Each of these copies of genes we call "alleles". If you read the DNA sequence of each of these alleles, they will be different from each other, and that's why they can result in very different physical characteristics of an organism (we call this the organism's "phenotype"). The different copies of a gene arise through gene mutation, and depending on the gene as little as a single mutation can cause a drastically different phenotype, depending on where in the gene or gene product (usually a protein) the mutation occurs. The allele for the white flower colour is incredibly similar to the allele for the purple (or pink, depending on who you ask) flower colour; so much so, that sometimes in the plant as it grows, one branch will generate a new mutation (a regular occurrence that happens in all biological organisms; this is how we evolve over time) that causes the exact same change in flower colour that having a different allele would. You might be looking at a single plant that has mostly pink flowers, then all of a sudden a short branch with 3 or 4 white flowers on it. It's amazing how our DNA works sometimes!

Aside from the colour-changing ability of the flowers, these flowers are highly praised for other reasons. They have incredibly high resistance to disease, including two fungal diseases that cause huge financial devastation in the ornamental rose industry: black spot of rose and rose rust. Many species of rose readily hybridize, so hybridizing the Japanese rose with any other species of rose can sometimes confer the benefits of increased disease resistance. Because it also has high salt resistance, it's a popular hedge plant for beside busy roads that get heavily salted during the winter. The rose petals retain their scent when dried, and so are a popular source of potpourri in Japan and China.

Monday, October 22, 2012

Resveratrol: the miracle drug from Japanese knotweed?

Species name: Fallopia japonica

Common name: Japanese knotweed

Location: Ontario

Again, from the common name of this species you should be able to discern that it's a non-native plant (native to Japan, China and Korea), and it is one that is highly invasive in disturbed habitats outside of northeast Asia. In North America, any place that it has been introduced it very quickly dominates, and takes many years of dedicated effort to eradicate it completely. Because of the intense underground network of rhizomes, complete eradication of the plant without use of chemical herbicides is nearly impossible; the next option is to dig up the earth and transport it away from the site (the easiest way to remove Japanese knotweed away from areas to be developed). This involves removing the top two to three feet of soil, a feat that is not possible for most natural or residential areas.

Despite this plant's bad rap, I find it one of the most fascinating plants we have in North America (but I would never plant it myself!). The growth rate of Japanese knotweed is outstanding; it can grow three to four METERS in one growing season from about May until October or November. That kind of growth in a temperate species in a temperate location is unheard of with very few exceptions. Why this plant isn't being investigated as a possible source of biofuel is beyond me (there's no reason why it couldn't be grown in a highly controlled way in a greenhouse or contained outdoor area, and genetically modify it to prevent the formation of seeds). The stems can grow to be so large and so strong that it is often mistaken for bamboo in the cut form (I doubt anyone would mistake it for bamboo when it's still standing in the ground; the leaves are very different! They are completely unrelated species).

In Japan, this plant is a traditional food crop, although not widely served in tourist areas so most foreigners are not exposed to it. The name for the food made from this plant (young shoots and leaves) is called "sansai," but the plant has numerous names based on different regions in Japan. When I was there in 2006, I was convinced to try it (in Hiroshima they call it "itazura") and boy oh boy. "Sour" does not even begin to describe it. I was offered a piece, I tried it, I didn't die, but I certainly wouldn't willingly inflict that kind of cheek-puckering pain on myself again! I didn't notice any reaction to it, but apparently the stems contain high levels of oxalic acid, the same chemical found in rhubarb leaves (and the reason why you should never, ever eat rhubarb leaves).

Today, Japanese knotweed is the most common source of the drug "resveratrol," which has an incredibly large list of reported benefits: life extension (unproven in humans, but works in mice and fruit flies), cancer prevention (no clinical trials in humans, but causes cancer cell death in cancerous red blood cells and smooth muscle like the lining of your intestines), cardioprotective effects (anecdotal evidence; all of the scientific evidence that showed resveratrol had any effect on preventing cardiovascular disease have been retracted because they were published fraudulently), antidiabetic effects (clinical trials have shown it lowers blood sugar), neuroprotective effects (has been shown to reduce plaque formation in the brains of non-human animals; no human studies), anti-inflammatory effects (prevents the progression of rheumatoid arthritis in rabbits; no human studies), antiviral effects (prevents the progression and spread of the herpes simplex virus and synergistically enhances anti-HIV drugs), effects on testosterone levels (increases sperm production in rats and increases testosterone production in mice; no human studies but is currently being sold as a bodybuilding supplement), and finally antimicrobial effects (shown to be ineffective at preventing growth of any microbe, bacteria or fungus, that it has ever been tested against). Should you choose to take resveratrol for any reason, make sure you consult your doctor.

If current medical uses weren't enough, there are also traditional medicinal uses of this plant. Both the Japanese and the Chinese in their traditional medicines used extracts from the leaves of Japanese knotweed as a laxative and to regulate bowel motility.

Sunday, October 21, 2012

Dear Europeans: please take your buckthorn back!

Species name: Rhamnus cathartica

Common name: European buckthorn, common buckthorn

Location: Ontario

The European buckthorn is native to (you guessed it) Europe, but also north Africa, and all the way east towards western Asia. It was introduced to North America in the early 1800s, and has since become a menace. The fruit start as green unripe berries, turn a pinkish-red (if you catch them that way; that colour doesn't last long), then a very dark black. These are a favourite fruit of birds, and it turns their poop an awful black-purple colour that is an absolute disaster to get off a white car. Interestingly enough, buckthorn seeds require the digestive and abrasive action of a bird's "waste management system" in order to germinate; unlike many tropical plant species that require the same germination mechanism, it can be any bird species. This shrub (or sometimes tree, depending on how much light and space it is given) is a great example of the idea that just because a bird can eat it doesn't mean a human can; the berries have a very strong laxative effect, and if enough are eaten they can cause severe dehydration (an effect that was exploited in the 18th and 19th centuries medicinally; it is no longer used for this purpose).

A couple of years ago the City of London did a tree survey based on aerial images and citizen reporting, to determine not only the percent cover of trees in London, but also the species of tree. I still don't quite understand how this worked with aerial images, since the resolution can only be so good; apparently they used some sort of combination of infra-red, ultra-violet, and true colour images to get a rough estimation of the species of tree. Sometimes the actual species could be distinguished, other times it was a vague common name like "oak tree" (which could apply to about 15 different species, some native and some not). The results were shocking, and yet they don't seem to have had any impact on species planted by the City. The top "tree", by leaf cover and by number of individuals, was the buckthorn (this is probably both glossy buckthorn and common buckthorn). The next tree was the Norway maple, another non-native and invasive species, and the tree rounding up the top three was either the sugar maple (number of individuals), or the black walnut (leaf area). Despite most of the trees in London being non-native and invasive species, there were two trees planted on my street this summer because of the ash tree purge (nothing like cutting down a native North American, healthy tree to replace it with a non-native invasive species): Norway maple and American elm (which will likely either succumb to the Dutch Elm Disease, or die from salt exposure; they are not salt-tolerant and so don't serve well as boulevard trees in a cold-temperate climate!). I still don't understand why we can't start planting trees that are not only native to our area, but also suitable for the given habitat. I can't possibly see how they're too expensive; you go out into a forest, collect some seeds, and put them into soil in a greenhouse. Free trees!

If the fact that buckthorns are invasive wasn't enough, to add to that they're also the alternate host for some of North America's most devastating agricultural diseases. They harbor the soybean rust and crown rust of cereals during the winter, and when the new crops are mature enough the fungi "jump hosts" and infect a new round of plants. While the soybean rust is not a huge problem in Canada (not yet, at least; it is being tracked by Agriculture and Agri-Foods Canada and is moving further and further north every year), it can be devastating for fields in the southern United States, leading to up to 70% crop loss in a single year.

Moral of the story: if you see a buckthorn in North America, grab a hacksaw and cut it down. Or you could do as was suggested to me by a friend and naturalist: "roundup vaccinations". Drill a bunch of holes in the trunk, and spray roundup in each hole. Act baffled when it dies later that season and has to be removed. Then suggest native species to be planted in that location instead!

Wednesday, October 17, 2012

That's one crabby apple!

Species name: Malus baccata

Common name: Siberian crabapple

Location: Ontario

The fact that this tree is the Siberian crabapple should lead you to believe it's a non-native species, and you would be correct. Amazingly enough, we do have native species of this tree in Canada and the northern United States (and one separate species in the southeastern US around Florida and Georgia) despite them hardly ever being planted as ornamental trees. I would think they would be more tolerant to the kind of weather we get in Canada, but the Siberian species is often favoured because of the scent of the flowers. The fruit are attractive in the late summer and early fall, but don't seem to be favoured by any species of bird or small mammal. There are some that will eat them, but birds seem to prefer the trees for shelter as opposed to a food source.

The pollination requirements of any species in the genus Malus is quite interesting. They all seem to be self-sterile, and require cross-pollination between cultivars in order to produce fruit. While this might seem like a detrimental process (what's the likelihood of two different cultivars being in close proximity?), it actually would give the trees a huge benefit in nature because it would eliminate the possibility of inbreeding and hence reduce the effect of detrimental recessive genes (that might cause disease, susceptibility to disease, malformation, etc.).

The fruit of this tree are edible to humans, but few people actually consume them. They are great for making jams and jellies, but not necessarily the most healthy because they are quite tart and require a lot of sugar to make them palatable. Greaves at Niagara-on-the-Lake makes a great crabapple jelly, if you're ever interested in trying some. The fruit do look a bit like cherries from a distance when they are fully ripe, but have a completely different texture. These trees are also very popular to be used as bonsai trees.

Tuesday, October 16, 2012

Birch bark canoes in tree form

Species name: Betula papyrifera

Common name: paper birch, white birch

Location: Ontario

This tree species is incredibly common in Canada, from the northern edge of the Carolinian forest north to the tree line. Despite being a deciduous tree, it is most common in coniferous forests like the Boreal forest. It is not shade tolerant, so is one of the first species to colonize an area that has been burned or deforested. It is also a popular ornamental tree for the attractive bark: white, peeling bark on the trunk, and reddish-brown bark on the twigs.

There are a few notable uses of the white birch. The first is in the lumber and construction industry. While the lumber generated from a white birch is not ideal for building anything other than ornamental pieces (chairs, tables, etc.), chipping the trunks and pressing them into boards gives OSB or oriented strand board, which is incredibly important in the housing industry. It is used most commonly as sub-flooring in homes (and as wall panels on which to attach other decorative surfaces), but also sometimes as sub-roofing (but is not very water resistant and so requires a membrane before the roof can be shingled). By far, the most substantial use of white birch today is in the manufacture of (drumroll) popsicle sticks.

There are unusual pockets of boreal forest that exist in the middle of the United States that are likely remnants from the last major ice age. Because it is now (more than likely) too warm for the white birch to happily exist in those locations, it is listed as threatened or vulnerable (or some variation thereof) in seven states: Tennessee, Colorado, Wyoming, West Virginia, Virginia, Illinois and Indiana. It is the provincial tree of Saskatchewan and the state tree of New Hampshire.

Historically, it was very important to Native North Americans as a canoe tree. There were two different kinds of canoes built from this tree, depending on the intended use. The first is to cut down a large tree and hollow out the inside to make a thin shell. These types of canoes weren't very common since finding trees large enough to do this is rare. Using bark pieces to form a waterproof barrier and shaping around a frame made of thin branches was much more common, and is still done in some areas today (although more of an ornamental canoe as opposed to one used for fishing and transport).