Dec 072017
 

The holiday season is the perfect time to get to know the conifers

With practice, it’s possible to identify many plants and animals by size and shape alone. Any two European starlings will always look plump, have a relatively long, straight bill and sport a short, square tail. In flight, the wings will appear triangular and pointed. The shape of trees, too, is remarkably consistent and often allows for quick recognition at a glance. Identifying distant trees against the winter sky adds enjoyment to any walk or car trip as you mentally compile a list of the species you observe. It is also a useful skill to have when pointing out the location of a distant object such as a bird. “Do you see the hawk perched at the top of the white pine over there? I think it’s a red tail.”

The holiday season is an especially appropriate time to sharpen our conifer (i.e., cone‑bearing trees) identification skills. Whereas deciduous trees are now bare to the sky, our conifers are dressed in their finest holiday foliage. Juxtaposed against their leafless neighbours, the unique contour of each species is easy to see. Christmas is also the time of year when we decorate our homes with evergreen wreathes, make winter planters and put up a real (the only choice!) Christmas tree. But, how many of us can tell the different species apart?

For each conifer group described below, I’ve provided hints for identifying the trees by shape and by characteristics of the needles. I’ve also included a memory aid or mnemonic with similar spelling for linking these characteristics to the name of the tree. (e.g., pine and pin).

Pines

Towering high above its forest neighbours is the eastern white pine, Ontario’s official tree and an iconic species of the Kawarthas. If you only learn the shape of one species, learn this one. The irregular crown and stout, wing-like branches growing at right angles to the trunk make this species instantly recognizable. The crowns of many white pines become one‑sided in appearance because of the effect of the prevailing wind. Jackson Park in Peterborough is crowned by a majestic stand of these imposing giants.

Although less common, the red pine is also native to the Kawarthas. Like the white, large sections of the trunk are visible almost to the top. The crown, however, is usually symmetrical. This species also has a very open, airy look with most of the needles grouped together in ball‑like “tufts.” This is because the foliage is crowded towards the tips of the branches. The scaly reddish bark is also a useful field mark. There is a stand of red pine planted on the south side of Lily Lake Road, just west of Ackison Drive.

A pine needle is like a long like “pin”. The white pine has bundles of five needles, which is the number of letters in the word “white”. Red pine has bundles of two needles. (Sorry, but red has three letters.) Care must be taken, however, not to confuse red pine with Scots (Scotch) pine, an introduced species whose needles also come in pairs. The red pine has long brittle needles (close to six inches) which break in half when bent. The needles of Scots pine are only half as long and are twisted. Just to confuse matters, the two-needled Austrian pine is another commonly planted conifer in cities and along highways. The bark, however, is dark brown to gray.

Spruce

Our most common native species is the white spruce. The entire tree has a near-perfect symmetrical appearance. The crown is cone-shaped or somewhat rounded. Most of the trunk is usually hidden by the bushy branches. The bark is gray and scaly, becoming darker with age. Spruce are particularly easy to identify this year because of the abundant cones, which are concentrated at the top of the tree. The cones of white spruce are about two inches in size.

By far the most common spruces in Peterborough, however, are the non-native Norway and Colorado (or blue) spruce. In fact, they are the most common tall conifers of any species in the city. Norway spruce are often planted around farms, too, where they serve as windbreaks. This species is easily distinguished by its large, horizontal branches from which secondary branches hang straight down. The cones, on average, are about six inches in length. Colorado spruce have a striking bluish colour, especially at the tips of the branches.

Spruce needles “spiral” all the way around the twig and are usually “stiff”, “spiky” and painful to touch. Because they are rounded, they roll or “spin” between your thumb and index finger.

Fir

The only fir you’re likely to see in eastern Canada is the balsam. Unfortunately, they are rarely planted as ornamentals and are therefore uncommon in the city. Firs have a near‑perfect symmetrical shape, but differ from spruce in that they are narrower and taper to a skinny point at the top. This gives them the nickname of the “church steeple” tree. The smooth, grayish bark of young trees is covered with raised sap blisters, which are fun to poke. This species makes a great Christmas tree, thanks to the wonderful balsamic fragrance, symmetrical shape and the long-lasting, dark green needles. Fir needles are “flat” and very “flexible”. You can’t roll them between your thumb and finger. Fir are most common in low, damp habitats on the Shield. Watch for them along Highway 28 north of Burleigh Falls. They also grow in Harper Park.

Hemlock

The eastern hemlock is another tree with a conical crown, but it becomes ragged and irregular with age. This gives the tree an untidy outline. Unlike the spruce and fir, the tip of the crown and other branches usually droop. Hemlock foliage has a feathery – almost lacy – look to it and the tiny cones can be found on even the lowest branches. While the white pine surely qualifies as king of the forest, the hemlock is my choice as the queen.

Hemlock needles are flat like balsam fir, but very short (less than an inch) and nearly white underneath. To connect the needles to the word hemlock – yes, it’s a stretch – think of the prefix “hemi”, which means half (e.g., hemisphere). Hemlock needles are half white (underside) and half green (topside). There are a number of spectacular hemlocks in Jackson Park, where they grow on the north side of the steep hill above the concrete bridge over Jackson Creek.

Cedar

By far the most common conifer in the Kawarthas south of the Canadian Shield, white cedars grow in dense, single-species stands or along forest edges. Trees growing in open environments such as fields are conical to almost columnar in shape and have a neat, trimmed appearance. The foliage is dense and often hides the trunk right to the ground. Forest-grown trees have a visible trunk and open irregular crown. The lower branches are usually dead. The bark, which matures into flat, stringy narrow strips, is shiny, smooth and reddish brown in young trees and grey in older individuals. This year, cedars are laden with an exceptionally heavy crop of small, tightly packed cones.

Cedars are unique in that they have scale-like, flattened needles. If you need a mnemonic – another stretch, I’m afraid – remember that cedar needles have scales, just like fish in the sea! (“sea”dar).

Juniper

The only tree-sized juniper in the Kawarthas, Juniperus virginiana, is usually known by its inaccurate common name of eastern red-cedar. They are small trees (usually less than 30 feet tall) and are most abundant in abandoned fields. The shape is variable, ranging from oval to columnar or pyramidal. The berry-like cones are dark blue in colour and often covered with a whitish powder. They are a favourite of robins and waxwings. There is a tall hedge of eastern red-cedar on the north side of Parkhill Road, just west of Wallis Drive.

Junipers have two kinds of bluish-green leaves: soft, rounded scale leaves, resembling those of the white cedar, and sharply-pointed needle leaves. The scale leaves can become yellowish-brown in winter. Both types of leaves often appear on the same branch. So, to remember the juniper, think of a pair of different kinds of leaves or juni”pair”.

Tamarack (larch)

Watch for these medium-sized, spruce-shaped trees in swampy lowlands, especially on the Shield. Winter identification is simple: the branches are bare because all the needles are shed each fall. In fact, you might mistake them for dead spruce. All that remains on the twigs are seed cones and some little protrusions or lumps, where the bundles of needles grew. Maybe think of “leafless larch”. There is a particularly nice stand of tamaracks on County Road 10, just south of Hooton Drive/Wilson Line on the west side of the road. They are beautiful in the fall when the foliage changes to a smoky gold.

Being able to recognize the various conifers that dot the landscape of the Kawarthas provides a very satisfying sense of place. Like the common loon and the white‑tailed deer, the pines, spruce, cedars, firs, hemlocks, junipers and tamaracks tell us we are home.

 

 

 

 

 

Nov 092017
 

Late fall is a great time to get to know these enigmatic structures

I’ve always loved November. Maybe it’s the change of pace and the sense of nature slowing down. Yet, we do notice changes. As deciduous trees shed their leaves, our eyes are drawn to the conifers like at no other time of year. They stand out in all their green splendor and beautiful shapes. And, if you look closely, you’ll notice something special this year: they are laden with a huge crop of cones.

You’ve probably held them, maybe used them to make a holiday wreath, but how many of us really know what cones are? The short answer is that cones – named after their shape – are the reproductive parts of an ancient branch of plants known as gymnosperms. Conifers form the largest group of living gymnosperms, but gingko trees also belong to this class of plants. About 300 million years ago, the gymnosperms became the dominant trees on the planet. They continued their dominance throughout the Triassic and Jurassic periods – the age of the dinosaurs. Their cones were even a favourite food of species like duckbill dinosaurs. The gymnosperms reigned supreme until the rise of the angiosperms – the flowering plants – during the Cretaceous period.

The arrival of gymnosperms was revolutionary, because it heralded the advent of the seed. This was as profound an evolutionary event as the development of the shelled egg in reptiles. Just as the egg allowed reptiles to become the first truly terrestrial vertebrates – and break nearly all aquatic ties – the evolution of the seed meant that plants no longer had to grow in moist environments like their fern and moss ancestors did. They could therefore colonize upland habitats. The gymnosperms protected their embryos from drying out by encasing them in a tough waterproof seed coat.

A closer look

All conifers produce cones. In fact, this is where the name “conifer” comes from. It is not accurate to call these trees evergreens, because some species, the tamarack for example, actually shed all of their needles in the fall, just like a maple or an oak. And not all cones are pine cones. This term only describes the cones of the pine tree. The cones of the other conifers should be named according to their parent tree.

Gymnosperms are different from angiosperms in that they lack true flowers. There are no petals, stamens, pistils or ovaries. In fact, the word gymnosperm actually means “naked seed”, because the seeds are not enclosed in an ovary. They simply develop from an ovule (egg) located on the inner surface of each of scales. Flowers, on the other hand, are produced by angiosperms, which include everything from oaks and maples to grasses and daisies. Angiosperm seeds develop when a pollen grain adheres to the stigma at the top of the pistil, travels down through the style and fertilizes an ovule located in the ovary. When you eat an apple and spit out the seeds, you are eating the enlarged ovary.

Male vs. female

As is the case with many flowers, cones can be either male or female. Both usually occur on the same tree. Junipers are an exception, having separate male and female trees. Let’s look at the female cone first. These are the typical hard, brown, woody cones. They consist of a central stalk surrounded by stiff, overlapping scales, reminiscent of wooden shingles. The ovules, which when pollinated become seeds, are located at the base on the inner surface of the scale. If you pry open the scales of a mature cone before it falls from the tree, you can often see the seeds inside. In white pine and balsam fir, the female cones are located high up in the tree at the tips of the branches. In most other species, they are found lower down, as well.

The male cones, also known as pollen cones, are much smaller (often only a centimetre or two in size) and far less conspicuous structures. Usually located on the lower branches, they are most often brown or reddish and resemble little spikes or buttons. They have a central axis, which bears pollen-producing structures. You’ve probably brushed up against them, causing a smoke-like cloud of pollen. Soon after the pollen is released, the male cones whither and drop from the tree. You will often see piles of male cones under pine trees in early summer.

Timetable

Each conifer species follows its own reproduction timetable. In the case of the white pine, Ontario’s provincial tree, clusters of male cones first appear in the spring at the base of new twig growth. A few weeks later, the soft, green and purplish female cones emerge. At the time of pollination, they are about two centimetres long. Towards the middle of June, the male cones release their pollen grains. The grains are so well adapted to wind pollination that they actually contain two air bubbles. Only an infinitesimally small amount of pollen ever makes it to the female cones, however. Most of it simply descends from the sky turning cottage decks, shorelines and puddles a lemon yellow.

At the same time as the pollen is released, the female cones become receptive to receiving the airborne sex cells. The tiny cone scales open slightly  and a small amount of fluid is secreted which serves to “trap” the pollen and draw it in towards the two ovules at the base of each scale.

Having secured pollen, the scales begin to thicken and to press tightly together. The cone continues to grow, hardens and turns from green to brown. Strangely enough, the actual fertilization of the ovules by the pollen only occurs 13 months later. It then takes an additional 13 months or so for the seeds to mature. In late summer, the scales dry out, flex backwards and open up one final time. This allows the seeds inside to simply escape to the wind. Each seed has a tiny wing, which helps it to float on the air, travelling up to 200 metres from the parent tree. In all, the process of reproduction will have taken over two years. The cones themselves drop off the tree during the late fall or winter, a few months after seed release. You can find them on the ground right now under almost any white pine.

Cone and seed development in all of the other conifers requires less than one year. In the case of white spruce and eastern hemlock, for example, the cones open and shed their seeds during their first fall or winter. The seeds often litter the snow. Spruce cones drop from the trees during this same period, but the cones of the hemlock remain on the branches until spring. White cedar cones also open in the fall and shed their seeds over several months.

With balsam fir – the best choice for a Christmas tree – the process is quite different. The scales themselves drop off the cone while it is still on the tree, thus liberating the seeds to the wind. All that is left is the bare, stick-like core of the cone. It can remain on the tree for several years. Balsam fir cones grow in dense groups near the top of the tree and stand straight up like candles.

In some conifers like junipers and yews, the scales on the female cone swell up and fuse together after pollination. This leads to the formation of a small, soft, fleshy cone, which superficially looks like a berry. You may have noticed the huge number of blue, berry-like cones on junipers (e.g., eastern red cedar) this year. Each contains one to four brownish seeds. Red cedar “berries” are very popular with birds like waxwings and robins.

Mathematicians

Cones are a testament to the wonder of evolution. The arrangement of the spirals of scales, for example, is anything but random. They follow nature’s numbering system, known as the Fibonacci pattern. It goes like this: 1, 2, 3, 5, 8, 13, 21, 34… (each subsequent number being the sum of the two preceding ones). If you look closely at a pine cone, you’ll see a double set of spirals, each going in a different direction. When these spirals are counted, the two sets are found to be adjacent Fibonacci numbers. For example, you might see eight spiraling counterclockwise and 13 spiraling clockwise. Larger or smaller cones can have different pairs of numbers. No, trees are not mathematicians. This arrangement is simply the best use of space, so it has been favoured by evolution.

Wreath

For a great holiday activity, you might want to try making a cone wreath. Going out to gather the cones themselves is half the fun. Try to find cones from different species. You’ll also need to make a cardboard base. The base can be cut into any shape you like – maybe a snowflake. Paint the cardboard or glue on a piece of felt. Then, using a glue gun, attach the cones to the base. If you spray the cones with water several hours before you begin, the scales will usually close and be easier to work with. Glue on the larger cones first, and then fill in the remaining spaces with the smaller ones. You can also add accents such as acorns and sumac berries. After the cones have fully dried and the scales reopened, spray the wreath with a clear lacquer. Handled with care, it will last for years and be a beautiful holiday reminder of the fascinating biology of cones.