trees – Page 8 – Seabrooke Leckie

Trees in bloom

The trees were all in flower when I was at my parents’ last week. Some trees have already flowered and finished, such as the cherry, but most of the trees were just at their peak, or on the downside of flowering but with plenty of blossoms left. I enjoy the flowering trees, and it’s a shame that their blooming period can’t last longer. However, I suppose it makes it that much more enjoyable while they do.

One of my favourites for its gaudiness is the crabapple. The tree in my parents’ backyard must be getting on in years as I can always remember it being there. Yet it continues to put on a good show in the spring. The tree’s proximity to the birdfeeders means it’s usually full of birds of different sorts, and in the spring the contrast of an Indigo Bunting or Blue Jay among the fuchsia flowers is particularly eyecatching.

The flowering trees that we typically think of are all fruit trees of one variety or another. Although many trees “flower”, the ones that produce these large, colourful flowers do so in order to attract polinators. Once the flowers are pollinated they set seed and develop fleshy fruits to attract animals, their primary seed-dispersal method. Other trees with less showy flowers usually develop seed pods or cases. This isn’t an exclusive relationship, however, as there are trees with large flowers that produce seed pods, and fruit-bearing trees that don’t put on gaudy shows like this.

The flowering tree that most people probably think of in the spring is the apple. There are several apple trees on my parents’ property, and all of them are also quite old, by fruit tree standards. Having never been pruned, they’re large, magnificent trees, which flower beautifully in the spring but don’t produce a lot of fruit. The apples they do grow tend to be small and usually slightly bitter; not so appealing to people, but the horses still love them.

The apple blossoms have a single style, the female reproductive organ, in the centre of the flower, surrounded by many anthers. Each flower blossom produces a single fruit once pollinated.

Although superficially similar in appearance, the hawthorn’s white flowers can fairly easily be told from those of the apple tree. They have many styles in the centre of each flower, each of which, when pollinated, produces a seed. The flowers also grow in “corymbs”, or groups, and the hawthorn fruits (called, appropriately, “haws”) form in clusters as a result.

Hawthorns are generally known for the long, sharp thorns they produce, but their flowers can be just as memorable. The hawthorn trees my parents have are also very large, having grown in the open, unobstructed by other foliage.

In the winter I clipped the infected branches from the chokecherry bearing Black Knot, and this spring it’s been blooming prolifically. Unlike the domesticated cherry, both chokecherry and black cherry produce flowers (and subsequently fruit) in long racemes. As a kid I liked to pick the stems of ripe fruit and slide my finger down it to collect a handful of berries; what happened to the berries after was less important, it was the satisfying way they popped off the stem that appealed to me.

This last one isn’t really a tree but a very large shrub, lacking a clear main trunk. The lilac is one of those that doesn’t produce fruit, but instead develops clusters of small seed pods. Like the others, the lilacs near my parents’ house have grown quite large, and over the years have produced fewer blossoms. They remain my favourites, though. I absolutely love the intoxicating smell of the clusters of flowers, and am sad when they finish blooming each spring. Someday, when I own my own house, there will be a large lilac bush planted at the corner.

Cats’ paws in spring

In the very early spring, one of my favourite plants to look for starting to wake up is the Pussy Willow. In my childhood I have fond memory of a large one that grew beside the second pond, in the horse’s field. I’m not sure why, because it wasn’t a tree I ever actually did anything with, not like the tree one has their childhood treehouse built in, or a favourite swing, or that one liked to climb, etc. It was just always there, and every spring it would be one of the first trees to waken from dormancy, putting out new soft buds. There were probably others in the area as well, but this was The pussy willow.

Back in mid-February, I actually found this one struggling to bud along one of the trails on the Rouge, the day Blackburnian and I went hiking there. Mid-February seems a bit early, and it may have been woken during one of the mild spells we had. Generally I think of them starting to come out mid-March, with the catkins reaching their peak in April.

Along with the dominant cottonwoods and birch, willow is one of the prominent tree species at TTPBRS. Most are the non-fuzzy kind, but there are a few Pussy Willow here and there as well. By the start of the spring season, they were well in “bloom”.

There’re three species of willow that have been given the common name of Pussy Willow, but the one that occurs in North America is Salix discolor. It’s only found in northern North America, through Canada and the northern States. Like most willows, it’s found primarily in wet habitats such as river and pond edges, swamps and bogs.

Like the sumac, all willows, including the Pussy Willow, are dioecious, meaning a plant is either male or female, but never sports both sexes of flower. The male flowers produce long pollen-producing anthers, which give them a fuzzy yellow appearance once they’re blooming. The female flowers develop stigmas, long thin tubes that lead down to the flower’s ovary, which are greenish-yellow and lack the fuzziness of the male flowers.

Willow bark contains the compound salicin, which is closely related to aspirin. Native Americans used to harvest the willows and extract the compound from the bark for use as a painkiller and fever reducer. Branches with the fuzzy white catkins are often used in flower arrangements in the spring, and harvested stems can be forced to flower in the greenhouse by manipulating light periods.

The Pussy Willow, like all willows, is a prolific grower and will grow a new tree from a severed branch if provided water. Although not a Pussy Willow, I recall as a child the willow trees along the road being trimmed around the power lines, and we ended up with a log with a small branch, probably no more than an inch in diameter, growing out of it. The log sat for a while on the lawn, and the branch flourished. Eventually my parents buried it beside one of the little ponds. This was perhaps 20 years ago or so; the tree is now easily over 20m (60 ft) tall and measures a foot and a half in diameter at chest height.

The name Pussy Willow, of course, comes from the soft buds that sort of resemble cats’ paws, in a very abstract way… they’re both soft and fuzzy. The pointedness of them makes me think more rabbit paws, actually, but I suppose Bunny Willow didn’t roll off the tongue as nicely? These would make nicer keychains, though.

The buds are eaten by birds, including finches and grouse, in the spring. Their dense branches make great shelter and nest sites as well. The leaves are a food source for caterpillars of a number of butterflies, and the male flowers are visited by pollinators such as bumblebees.

Personally, I like to gently stroke the deliciously soft catkins against my cheek. I’m not one for fur, but I’d love to have a muff made out of these – with the fur on the inside, of course!

Tunnels from top to bottom

When I sat down to enjoy the sunshine and do a bit of sketching in the Don Valley trails on Sunday, I chose a young sapling to sit in front of. Not for any particular characteristic of the tree, but just that I like to have something at my back. I didn’t pay much attention to the tree initially, and I hung my camera bag on a broken-off branch before sitting down. When I got up and reached for my bag, I happened to notice these lines on the bark.

They’re obviously made by some sort of insect. Curious to what it may have been, I started poking around the ‘net. The answer to this question was not nearly as easy to find as I had expected it to be. Between yesterday and then again today I’ve spent several hours typing in search terms into Google and checking out promising links. This is easily the longest I’ve spent on researching a post to this point, and I didn’t even come up with anything conclusive for all that effort.

Research for my posts usually starts with a single, rather vague, descriptive term. For instance, when I was researching the Black Knot information, my first term was “black crusty growth on twig”. You usually get a few misses at first before hitting on to what’s obviously the correct identification. In this case I started off with “bark miner”. I’m familiar with leaf miners, which create tunnels between the two surfaces of a leaf, and this looked very similar. It seemed like a pretty obvious connection, but the search produced no viable hits. I changed my approach. “mines under bark lines on surface insect branch”.

This turned up a lot of not very useful stuff, but did contain one page that had something. It was a fact sheet on the Allegheny Serviceberry. What does that have to do with insect mines? It had a section on pests. The first paragraph read, “Cambium miners cause concern when noticed but are not very damaging to the tree. The mines can extend from a twig all the way down to the roots. The mines form light-colored lines in the bark.” Aha! A lead!

So the next search term was “cambium miners”. The cambium is the layer of reproducing cells in a tree located between the outer bark and the inner hardwood which is the source of the tree’s outward growth. It’s just a narrow layer, and in a young thin-barked tree like ash, maple, birch, and other deciduous species, it’s pretty close to the surface. This seemed promising.

Most hits I found just simply called them cambium miners, without identifying the species or even the order of insects they belonged to. I didn’t find this especially useful. However, after poking through a number of hits I came across a page from an online resource called Tree Dictionary. The page seemed to be focused on pests of trees as well, and included a lot of information on various fungi. Also paragraphs on sapsuckers, squirrels, frost, beetles, and, the object of my search, cambium miners.

The page indicates that cambium miners are flies belonging to the genus Phytobia. The flies lay their eggs on branches near the top of the tree, and the young larvae mine their way through the cambium down toward the roots, where they stay till they pupate. There isn’t actually a lot of information on the life history of this genus on the web, at least that I turned up in my initial searches. I was able to determine that there are a number of different species that have different host preferences, and some are cambium miners while others are leaf miners.

Knowing the species of my tree would help. I’m not certain, as it’s a small sapling in the middle of winter with no leaves. I can rule out birch fairly safely, I would think, and cherry, because there aren’t any horizontal lines. Beech and maple would be grey. Hawthorn would have spines. But that still leaves me with an assortment of options, including common species like ash, and less common ones such as alder, hickory, etc. I’m leaning toward ash, given the location and its commonness.

On the website ForestPests.org I found an informative factsheet on the Ash Cambium Miner. The page indicates that the larvae of this fly mine in straight or serpentine tunnels near the top of the tree, but the further down they get (and presumably, the older they get), the more their tunnels take on a zig-zagging appearance until they’re distinctly so by the time they reach the roots, where they’ll spend about 10 months. They overwinter there, then exit the roots in late spring and pupate in the soil.

I continued to poke around, pressing on and changing the search terms to see if I could turn anything else up. I had a few other potential culprits, including flat-headed borers (metallic wood boring beetles, the group that includes Emerald Ash Borer), and small moths of the genus Cydia, but none of the online resources seemed to match as well. I’m still not positive on calling them Phytobia sp, either, given that I couldn’t find any resource showing their mines to be able to compare to the ones I photographed, but the information all seems to match pretty well.

Today I spent the day laying laminate floor in the family room at my parents’ house. I’m pretty sure that laminate wood flooring is a little like vinyl tile in that they make the wooden planks out of pressed particleboard (or something resembling it) and then print a design on top, rather than laying an actual wood veneer over it. However, I assume they use an actual image of woodgrain to create the print image, so the laminate planks represent actual woodgrain patterns.

What does this have to do with cambium miners? Well, on both of the sites mentioned above, they indicate that the mines left by the larvae get grown over as the tree continues to grow and result in small discolourations in the wood. These show up as small dark marks on stumps when the tree is cut or, as in the case here, in wooden planking, where they’re called “pith flecks”, among other names. They apparently don’t show up in ash wood very well, but are fairly noticeable in most other types of wood. I’m not sure what type of wood this laminate is supposed to be an imitation of, but it’s got a distinctly reddish tinge.

Here’s a close-up of the pith flecks in the woodgrain of the laminate print. You can see nearly all of them are associated with the tree-ring growth mark, where the larva would have been tunneling close to the surface of the bark (the dark growth line). A couple of the marks are further in; apparently there are some species that will occasionally feed in the xylem (the layer under the cambium) for short periods, and that could be what these are.

Despite that these marks are due to insect damage, they’re not generally considered defects of the wood by most lumber manufacturers, but they are recognized as such by the Fine Hardwood Veneer Association (who knew there was such a thing?). I suppose that, over the course of a tree’s life, there’s a good chance it will be infested at least once so it would be hard to completely eliminate the marks from wood products.

Insects. They’re everywhere.

Walker’s Woods in winter

I am not, and never will be, a city girl. I’m here currently mostly because of circumstances, rather than choice. I grew up in the countryside, and find myself going a little stir-crazy if I’m stuck in the city too long, or if several of the city’s inconveniences pile on me at once. The problem with being in the city is that in order to get anywhere to go for a hike in a natural setting to relax and calm your mind generally requires a bit of an undertaking. It becomes a concerted effort, instead of a quick pop outside to hike through the woods at your backdoor, as it was as a kid, and any outing usually kills half your day, rather than being a short hour-long hike. As a result, I don’t get out nearly as much as I might like.

Today we decided to visit a TRCA property northeast of Toronto. It’s called Walker Woods, and it, along with the neighbouring Glen Major Forest, are sites in consideration for possible future expansion projects of the Tommy Thompson Park Bird Research Station (a project of TRCA). The outing had the dual purpose of getting outdoors, and having a first look at the general area to assess the landscape.

The snow was deep, and we kept to the trails, which had been flattened by many cross-country skiers. The footing was still slippery, though, as the snow wasn’t hard-packed and your toe would dig into it as you walked, a little like walking on a sandy beach. After walking a little distance we decided to loop back along a trail branch that would take us back to the road and try driving some sideroads to look for open-field birds or, if we were lucky, perhaps a flock of berry-eating Pine Grosbeaks or Bohemian Waxwings. We found neither, though I did think as we were starting to head home, along a busier street, that I caught a glimpse of a Northern Shrike perched atop a spindly little tree in a field.

Much of the area we walked was these pine plantations. Likely planted either as windbreaks, back when this landscape was still mostly used for farming, or for commercial harvesting, they have very characteristic, obvious linear formations. These sorts of plantations look unnatural, because of the pattern of the trees and their uniform age, and I don’t even feel make great habitat because they lack the diversity of structure that encourages many species to inhabit the woods. There’s no understory. The only small plants growing there were small pine seedlings, and even these were few.

At one spot along the trail there’s an old shelter, which looks like it may have been used to house either farming equipment like tractors, or hay bales for storage. Given its placement in the woods, it seems like an odd place to keep either, but it’s possible it hasn’t been used in a while and the young forest had since grown up around it. Or, if it was used to house equipment, that could be brought in through the trees.

A bit further down the trail I spotted the remains of this foundation, slowly growing in with young saplings, possibly black cherry, and a couple of birches. Presumably this was the homestead that went with the old storage shed, but it could also have been another barn or outbuilding.

We walked back along the road to where we had parked the car. In several sections the fence was overgrown with vines and dried goldenrod. I didn’t take a close look at the vines, but I’m not sure that I’d be able to tell the difference between wild grape and Virginia Creeper without their leaves. I scanned these open fields and the fenceposts that lined them for any small white lumps that might reveal themselves to be Snowy Owls, but with no luck.

In many spots along the trails there were young beech saplings, brightly coloured against the white snow and dark evergreen forest as they retain their dried leaves throughout the winter. The phenomenon is called marcescence, and applies in this case to leaves withering without falling off. There’s some debate about the reasons it happens, but it’s noted only to really happen on very young sapling beech or the lower, young branches of older trees. I read a good blog post about it recently, but I’ll be darned if I could find it now to link to it. (Edit: I just found it. It’s posted by Carolyn over at Roundtop Ruminations.)

On the drive home I noticed a number of flocks of geese heading north over the fields. I associate these sorts of large, multiple-flock movements with migration so… hopefully a sign that spring is on the way?

Cattail thwacks revisited

Edit: This post was recently included in the 180th edition of Friday Ark, a weekly blog carnival focusing on animals of all sorts. You can check out the full edition at The Modulator.

One of the downsides to learning things yourself using the internet or reference books as your guide is that it’s pretty easy to mis-identify something based on poor photographs, incomplete descriptions or information, or just vague or ambiguous wording, particularly if you have a notion about what you’re expecting. In one of the posts I did mid-January, about fungus in the woods in winter, I mentioned a large, creamy, fuzzy mass I observed on the trunk of a tree that I identified as a slime mold. Well, Jennifer over at A Passion for Nature corrected me on this by (correctly) suggesting that it looked like a gypsy moth egg mass.

I went back yesterday to the same area and had another look at it. The particular one I photographed still looked and felt (to my frozen-numb hands) like a cattail thwack with no particular distinguishing characteristics (I didn’t want to try taking it apart because I don’t like to disturb). However, upon closer investigation, I started noticing more of these fuzzy blobs on nearby tree trunks, pretty much all within a few feet of the ground. Some of them had much more obvious visual characteristics that may have led me to the eggs conclusion if I’d seen them first. In the above and the first photo you can actually see the individual eggs wrapped up in all the little hairs that create the fuzzy mass (I think the first photo may actually be hatched eggs from last year? It’s hard to tell, but the dark spots are very pronounced). The hairs are made by the female moth as she’s laying her eggs, and are hypothesized to protect the eggs from potential rodent and avian predators by discouraging them from getting the hairs in their face and nostrils and irritating the skin.

Gypsy Moths aren’t native to North America (like a lot of common wildlife). Rather, they were brought over to Medford, Massachusetts in 1869 by French astronomer Leopold Trouvelot, who also had an interest in insects and was hoping to breed a sturdier, more productive silkworm. Well, like often happens, the moths escaped and it didn’t take them long to settle into the new landscape. They’re now found into eastern Canada as far north as Maine and the Maritimes, as far south as northern North Carolina, and currently west into mid-Wisconsin. When you consider the size of the insect in question, it’s a pretty good area to cover over that period.

The moth’s dispersal is also made more interesting by the fact that the female moth, the recognizable white Gypsy Moth, can’t fly. When she emerges from her pupa she’s full of eggs and way too heavy to get airborne. Male moths (which are brown) can fly, and will travel long distances to reach a female, which they detect using the broad, fluffy antennae that only males possess. These antennae are specially designed to pick up the pheromone molecules released by the female when she emerges. Near a couple of the egg masses I found pupa cases left from the female when she emerged. The cases also have hair tufts that presumably protect them the same way the hairs in the egg mass do.

Still, if the females aren’t moving, then the eggs are going to be laid near where the female emerges, which also doesn’t help much with dispersal. Instead, dispersal is carried out by the caterpillars (weird, eh? The only ones without wings). Caterpillars, during the course of their feeding, climb to the top of the tree and then spin a line of silk which they use to “balloon” on the wind over to the next tree. I can’t imagine this taking them very far, so it would be a very slow dispersal.

This photo (used with permission) is of a female caught in the act of laying an egg mass in late summer. She was found inside a porta-potty, so I can’t imagine the caterpillars would have much to eat when they hatch, but I gather Gypsy Moth females aren’t too particular about where they lay their eggs. The larvae will feed on up to 500 different species of trees, but particularly favour oak. Most of the egg masses I came across were on rough-barked tree species, primarily Black Cherry. Caterpillars hatch from their eggs in early spring, late April into early May. They feed on tree leaves and can be a severe pest in some areas where they completely denude trees of their foliage, particularly since a single egg mass can contain up to 500-1000 eggs. In late June to early July they begin to pupate, and emerge as adult moths after a couple of weeks. Females lay egg masses shortly after emerging, and adults will never eat. Adults die shortly after mating, and the species overwinters in the form of these egg masses.

It’s funny how once you know to look for something, it suddenly seems to jump out at you everywhere. Now that I’m aware of these and what they are, I’ll be keeping my eyes open for them on future walks.