Showing posts with label phenotype. Show all posts
Showing posts with label phenotype. Show all posts
Tuesday, July 16, 2013
A joy for travellers to see
Species name: Clematis x jacksonii
Common name: clematis, traveller's joy
Location: My house (London, Ontario)
Clematis plants are some of the most interesting plants to me because of their quirkiness and eccentricities. They don't follow the "aesthetic rules" that most flowering plants do, and that's definitely one of the things that makes them so cool. This species, a hybrid between two Asian species then hybridized again with a common garden species popular in the late 1700s in gardens in Europe (the history of this garden hybrid is unknown, but likely from Asian ancestors, too). Due to the fact that this plant is a hybrid it technically carries no weight according to the IUCN Red List of endangered and threatened species, but I can vouch for the fact that this plant is not likely to spread, nor is it likely to reproduce and escape from the garden. We moved into our house in March of 2006, and I've never witnessed this plant producing seeds (which are actually quite spectacular; they're like dandelions with a bad hair day). Not good if you're the plant, but great if you're the gardener that doesn't want to clean up after the plant!
The second image shows the twice-compound leaves, which branch twice into three. The leaves are produced oppositely on the stem (the purple arrow points to where the petiole, or the "leaf stalk", attaches to the stem and you can see that there's another leaf growing off the stem in the same place in the opposite direction), and each petiole divides into three at a single point (you can see the path the petiole takes in yellow). From there, the petiole divides into three again, and at the end of this division there are three leaflets (red arrows). Sometimes leaves can do some strange things and not obey the rules. Instead of producing a leaflet at the end of the petiole, sometimes the leaf turns into a modified structure for climbing: a tendril.
In general, there's a lot of misconceptions about "specialized" plant organs used to attach plants to houses or climb up support structures. Peas are well-known for their tendril producing abilities, and clematis vines should be, too. Clematis vines produce very little growth from their old stems; they much prefer just to send up new shoots from their rhizomes just under the surface of the soil. If you consider just how much this plant has grown in a single growing season, obviously the height of the vine would produce too much weight for the plant to handle on a skinny non-woody stem. To help hold it upright, tendrils are produced to wrap around support structures. These tendrils originate from the leaf, and if you cut straight through a tendril and make a very thin cross-section and look at it under the microscope you'd notice that a tendril has the structure of a rolled-up leaflet. Pretty neat! These tendrils have another secret ability: they respond to touch. Have you ever wondered why a tendril coils? It's not because one side is produced "smaller" than the other and so it spirals to compensate for the lack of space. It's actually the plant that senses a suitable object is touching the tendril and has been for long enough to provide support, and the tendril will start bending towards that object as it grows. If you're REALLY patient (and I mean you would give a saint a bad name with your level of patience) and have a lot of time on your hands, take a tendril that's grasping at something to curl against, and hold your finger against it for maybe 30-60 minutes. Try to move as little as possible, but a little movement is OK. After your hour is up, you can walk away and return to your clematis the next day. What happened to the tendril? I bet it will have super-coiled around itself and made a mass of curly tendrily mess. There was a signal that the plant received when your finger was against the tendril that said "SUPPORT!!! COIL QUICKLY!!!" and it responded--just too late to be useful. You've now manipulated a plant into reacting to your touch. Pretty cool! See, manipulating plants for your own amusement can be fun...
The flowers of this plant are also incredibly unusual. There are flowers that produce four petals, five petals, or six petals (the majority seem to produce five). If you think that all of the flowers just had six petals and some lost a few before I took pictures of them, I also managed to find one of each version that was just getting ready to open, so I can definitely exclude that as an explanation. Why does this happen? As far as I know there's no explanation. None. Completely stumped. Our clematis grows in the shade, so I thought perhaps it was just confused and suffering from a lack of sun (these plants definitely prefer full sun or at minimum partial sun to be most happy) but I just looked up pictures of the plant on Google Images and there are people growing theirs in full sun and noting the same phenomenon. Find an explanation for why this happens? Let me know! I've always been interested in learning about why this happens.
Other than their obvious ornamental value, some clematis species (there are over 300 of them) have been used in North America as medicinal plants for centuries. It was used to treat nervous diseases and migraine headaches, but don't get excited about the medicinal properties of the plant in your back yard. Most clematis species are highly toxic, and the sap that's exuded from cut stems is highly allergenic, is phototoxic (meaning it will cause extreme rash and burning when the sap on your skin is exposed to intense sunlight), and can cause internal bleeding if ingested. This plant is best used as an ornamental species and not a backyard medicine. It's also probably best to use gloves when pruning this plant; some people are more sensitive to the toxins in the sap than others, but always better to be safe than sorry. The phototoxic effect can last for years, despite washing the sap off your skin.
Sunday, May 5, 2013
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.
Saturday, December 15, 2012
A Rocky Mountain Juniper
Species name: Juniperus scopulorum
Common name: Rocky Mountain juniper
Location: Ontario
As the name suggests, the Rocky Mountain juniper is native to the Rocky Mountains in North America, from British Columbia all the way south into Mexico (although, there are so few populations left in Texas and Mexico that the range should probably be amended to say it ends in Arizona; this very suggestion has been put forth by the USDA more than once). It thrives in high altitudes where it is common and a relatively short tree (as most alpine species are), but incredibly long lived. In New Mexico, one was felled that was estimated to be 1,500 years old, and a standing dead tree was found to have 1,888 tree rings. There are some individuals left in Arizona that are estimated to be 2,000 years old or more. Incredibly enough, these aren't even the oldest living trees on Earth...
Those of you who live on the west coast and have seen this species in their native habitat on mountain sides will probably be pretty jealous of the height of this individual on campus. It was probably planted when Talbot College was built in about 1970, so the tree would only be 40-50 years old. It's already much taller at 50 years than other individuals would be after 750 years or more! Just goes to show that when you plant species outside of their native habitats, strange morphologies can be achieved.
Like all gymnosperms, the "berries" produced on the branches are not fruits, no matter how they might appear. Gymnosperms, unlike angiosperms, do not have flowers and so don't have all the layers of tissue required to produce a true fruit. Despite this fact, ginkgo (which you can read about HERE), yews (which you can read all about HERE and HERE), and junipers all produce berry-like "fruits" that are just modified seeds. The outermost layer of the seed is modified to store starchy and sugary compounds, often with a lot of waxes and resins to protect the seeds from predation by small animals, and are produced instead of cones. Another interesting fact to note about this species of juniper is that, like ginkgo and holly, the tree is either male or female but never both. The bright blue modified seeds are produced on the female trees, and the male trees have pollen cones that are produced in the spring and release all of their pollen into the air right around spring allergy season. It seems like in the spring and fall, all of the trees conspire against humans to irritate our airways! Sometimes the blue berries are produced regardless of whether the male tree is present or not, but the seeds inside will not be viable. Like holly and ginkgo plants, if you want to ensure the success of the seeds you need to plant both sexes in close proximity.
Many junipers have traditionally held a strong importance in the lives of native North Americans due to their medicinal value. The bark of the Rocky Mountain juniper is boiled to make a tea and consumed to treat coughs and fevers. Since there are so many resins produced by this species (the yellow "sap" that drips down the outside of the tree, especially after the tree has been wounded) have great antimicrobial properties, and are actually the very reason the tree produces them in the first place! I have strong suspicions that any time the bark of a gymnosperm is cooked to extract the resins then consumed, it will have a strong effect against bacteria in the mouth and throat. This doesn't mean you should attempt this, however; some resins produced by various species of gymnosperms are highly toxic and should never be consumed! It's always a fine line in herbal medicine between things that will make you very ill and things that will help your sickness. Mixing your own concoctions just to try things out is strongly discouraged.
Thursday, December 13, 2012
A cold-tolerant eucalypt
Species name: Eucalyptus gunnii
Common name: cider gum, eucalyptus
Location: Ontario
For anyone from Australia, to see any eucalyptus plant in Canada outdoors would probably be surprising. In fact, it's not just Australians that would be surprised; this Canadian was mighty surprised, too. I was shocked to see that the campus landscapers would have thought this plant was going to survive in our climate, which is inhospitable to tropical trees to say the least. To my surprise, the more I read about this plant the more I wanted to put one in my back yard for novelty sake; it's actually incredibly cold tolerant! This species of eucalyptus will readily survive winters with extended periods below -10 degrees Celsius, and can even survive short periods below -20 degrees Celsius. It's still not a good idea to trust this plant to a harsh Canadian winter, but finding out it could survive snow cover was a surprise to me. This is actually becoming a popular garden plant in Europe since it has the attractive evergreen foliage of a eucalyptus (and the incredible smell) while not having to be taken indoors every winter.
All eucalyptus trees are native to Australia and the surrounding area, but most have been successfully transported outside of this restricted area for ornamental and medicinal use. This particular species, the cider gum tree, is native to a very small area in Tasmania. Like Madagascar periwinkle (which you can read all about HERE), there are few individuals left in the wild in its native range, despite being so incredibly common in other locations in the world due to its ornamental value.
One spectacular morphological characteristic of this plant that is rarely seen to this degree in nature is the morphological variation of the leaves along a single branch. The leaves start off almost circular, with a very short (sometimes absent) petiole at the base of the leaf. The leaves spiral around the branches of the tree, and are a brilliant grey-green. As the branch grows longer, the leaves also elongate until they look very similar to willow leaves, and there is a change in colour so the leaves are a much darker, deeper green. If the tree is pruned into a shrub (as is most common in an ornamental plant setting), the shrub will retain its juvenile leaf form and never progress to having elongate leaves.
While this species of eucalyptus is not often used for anything other than as an ornamental plant, other species in the genus are used for their essential oils, which are very powerful antibacterial chemicals, insecticides, and even industrial solvents. The oils are sometimes also added to food, but only in very minute quantities (the saying "a little goes a long way" is absolutely true in the case of this plant, but also even moderate amounts of the essential oil when consumed is toxic to humans). The tree's leaves are the main food source of the koala, an animal often regarded as the "icon of Australia". Eucalyptus trees are also known as "water-suckers" since they can completely dry up a swampy area in only a few years, turning the soil into arable land. This doesn't last long, however, and the land quickly converts to desert after only a few growing seasons. The wood of eucalyptus trees is very quickly produced, and so it was once considered as a biofuel before being abandoned for other crops that were easier to care for.
Labels:
antimicrobial,
at risk,
biofuel,
cider gum,
essential oil,
eucalyptus,
Eucalyptus gunnii,
evergreen,
insect control,
leaves,
Madagascar periwinkle,
medicinal plants,
non-native species,
phenotype,
toxic plants
Thursday, December 6, 2012
A Frankenplant or the real thing?
Species name: Hydrangea quercifolia
Common name: oak-leaved hydrangea
Location: Ontario
Those of you who have never seen this plant before probably looked at the leaves and thought "hey! I recognize those! That's an oak!" and then looked at the next two photos and thought "gee, she's awfully good at photoshop. Those leaves and flowers don't belong together!" Well, you would have been in good company in that boat of confusion; when I first saw this plant a couple of years ago I thought someone had created a Frankenplant by grafting two completely different species together (which is possible, but usually they're at least in the same or closely related families. Hydrangeas and oaks are nothing alike, and don't share a recent ancestor). The oak-leaved hydrangea is a real plant, "created" as a product of evolution and natural selection, not garden novelty and artificial selection. It is native to North America as far north as Tennessee and as far south as Florida, from the eastern seaboard all the way west to about Louisiana. It can grow quite happily in southern Canada despite our cold winters as long as it is either drastically cut back in the spring to prune off all the dead growth (the winter will kill any overwintering buds; most of the new growth comes from the rootstock in Canada), or planting it in a very sheltered area from the harsh winds and the weight of the snow. Building a "burlap teepee" to put over the plant to protect it during the winter would be a good thing if you plan on keeping it around for a while; if not just a good hard prune in the spring and you'll be good to go. Just don't expect many flowers since those only grow off of at least one years' growth.
The oak-leaved hydrangea is a perfect example of phenotypic plasticity; that is, a plant's ability to modify its appearance based on environmental conditions. Often, this is a slow process involving changing growth patterns over weeks or even months, but in the oak-leaved hydrangea during peak growth times it can be in as little as hours. During times of drought, the plant actually has the ability to reabsorb nutrients from its flowers to put back into the leaves and sustain its basic life functions: making sugars from water and carbon dioxide, then breaking down that sugar again into energy. The flower buds will look completely healthy, but if the plant is experiencing a prolonged drought then all of a sudden it seems like the buds are withering and they turn brown. Those buds will never develop into flowers, but if you give the plant a good watering as soon as you notice it, new ones might form if you're lucky. The plant can also modify the appearance of its leaves; after a prolonged drought the leaves will be more prominently lobed with less leaf area. If the growing conditions are ideal, then the leaves will be much fuller with more tissue between the main veins. You can almost think of it like the difference between a pin oak leaf (which you can see HERE) and a white oak leaf (which you can see HERE). A pretty drastic change!
Tuesday, November 27, 2012
One of the Austrian pines
Species name: Pinus nigra
Common name: Austrian pine, European black pine
Location: Ontario
The Austrian pine is native to Europe, in countries surrounding the Mediterranean and Baltic Seas. There are actually two subspecies of the Austrian pine which rarely interbreed (but are still capable of forming hybrids in a very small overlapping zone as well as when they are brought together under artificial conditions like a greenhouse): the western subspecies existing in southern Italy, southern Spain, southern France and North Africa and the eastern subspecies in Austria, central Italy and Turkey. The needles of the two subspecies are quite different and you can easily tell them apart when side-by-side; the needles of the eastern subspecies are much fatter and much more rigid than the western subspecies. They both have different liveable temperature ranges, too, with the eastern subspecies being able to tolerate much colder minimum temperatures (down to -40 degrees Celsius with no adverse effects) compared to the western subspecies (only about -25 degrees Celsius or so). I believe the subspecies on campus would be the eastern subspecies, P. nigra subsp. nigra.
One major attractive feature that probably led to its widespread planting across Europe and North America is that it is a very fast growing tree, relative to other needle-bearing trees. It was originally thought to be an excellent lumber tree, so it was planted in large numbers in North America. Unfortunately, the grain of the wood is very rough and quite variable across the height of the tree, so making long boards suitable for building is not feasible. It was turned to as a major source of pulp and fibres for making paper, as a fuel source, and is still used as a low-grade wood for some construction purposes.
Unfortunately, as with most plant species that have been transported out of their native range, the Austrian pine has a dirty secret. That secret is a fungus. The "red band needle blight disease", caused by the fungus Dothistroma septosporum, is especially toxic to North American Austrian pine trees because of their inability to breed properly here. Austrian pines have a hard time cross-breeding outside of their native ranges, and the seeds that are self-fertilized are much less likely to germinate. This causes something called "inbreeding depression," which can lead to a buildup of genes that make a tree (this happens in animals, too) more susceptible to a pathogen. The North American trees are very susceptible to this pathogen, and it is an almost certainty that every single Austrian pine tree in North America will succumb to this disease. There is no known treatment once a tree is infected other than cutting it down and burning the residues (especially the needles, where the pathogen is housed in the living tree). Planting this tree, even as an ornamental, is strongly discouraged and planting this tree in continuous stands is not only strongly discouraged, but carries quite a hefty fine if you're caught doing it in many states in the United States (but no provinces in Canada yet). You can see that the tree in the top picture is looking very unhealthy; it is likely showing the first signs of infection from the disease.
Saturday, November 3, 2012
The mighty white oak
Species name: Quercus alba (hybridized with...?)
Common name: white oak
Location: Ontario
I took this photograph of a white oak on campus, and I doubt it's a "pure" white oak. The swamp oak (which you can read about HERE) and the white oak are not only very closely related species, but they also readily hybridize. For anyone to sell a "pure" white oak, I would like to know how they did it. Collecting acorns in the wild and growing up trees in a nursery (then repeatedly harvesting nursery acorns and replanting to grow up your stock) will almost always result in hybridized white oaks. And if the tree nursery also grows swamp white oaks, they've compounded their problem. In fact, oak pollen is so light and can travel so far on wind currents that you don't even have to know where a swamp oak or a white oak are to get them to hybridize. Like the issue with the Freeman maple (which you can read about HERE), once these two species hybridize they often get intermediate features, or a "blending phenotype." Oak pollen is actually one of the leading causes of seasonal allergies in the spring. Anyone living near an oak tree can attest to this; my dark grey car often takes on a yellow tinge because of our big red oak growing in the front yard.
The white oak, no matter its genetic background, has been used for centuries as one of the most prized woods in the world. Because of the structure of the cells in the wood, it is completely watertight when used for making furniture or other items. These same cellular structures make it rot-resistant, which is why it is so popular in the use of barrel construction; the liquid won't leak out of the barrel, and if it does start to become saturated with the liquid inside it won't rot and release the contents. Not cracking and breaking apart is probably preferred during the alcohol aging process! It's not just wine that's stored in oak barrels, but also rum and whiskey. Since some rums are aged for 20 years or more (an Appleton Estates rum to be released this year is a 75 year aged rum, all done in oak barrels), putting them in a barrel that's likely to rot or leak is probably not preferred! The watertight and rot-resistant characteristics also make oak a popular wood historically for shipbuilding and agricultural construction (both equipment and barns).
On the inside of homes, oak is a popular wood for visible finishings. Sometimes cabinets are made out of a different kind of (cheaper) wood, then the front facings are oak. Oak flooring is also incredibly popular, and often it's even stained to resemble other, more expensive woods (like cherry, walnut or mahogany). In fact, most mahogany flooring sold today in Canada is just white oak wood stained a reddish colour, since international trade treaties have been signed preventing the import of South American tropically-grown mahogany wood into Canada. Since the term "mahogany" doesn't actually apply to any one species of tree (unlike wood from black walnut, white oak, sugar maple, white pine, etc.), that eliminates many options for sourcing mahogany! While I'm sure mahogany is incredibly popular to use for fine furniture and household finishings, South American rain forests are being eliminated at an alarming rate for both the international wood trade, and conversion to the North American style of farming (higher productivity for a few years, but then a drastic decline in productivity due to the low level of nutrients in the soil). By preventing the import of these trees, we are doing our part in attempting to conserve the tropical forests in South America.
There are some notable famous white oaks across the United States. The first isn't one tree, but actually an entire grove of white oak trees. The USS Constitution is made entirely of white oak, and whenever parts of it need to be replaced they come from a grove of trees called Constitution Grove near Bloomington, Indiana. The states of Connecticut, Maryland and Illinois have all made the white oak their state trees, with one specific oak representing the honorary tree of the state. The Charter Oak in Connecticut is even featured on the back of their state quarter (which I, of course, proudly own since it features a botanical design). The honorary state tree of Maryland, the Wye Oak, was one of the oldest living trees in the United States until it was destroyed in a storm in 2002. In Illinois, they couldn't decide which tree they liked better to serve as their honorary white oak so they picked two; the first is on the front lawn of the governor's house, and the second is in a school yard. The new largest living white oak is the Linden Oak, also located in Maryland.
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.
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