Sandra's Garden: When two become one

Species name: Picea sp. (probably Picea mariana)

Common name: spruce (probably black spruce)

Location: Sandra's garden

The reason why I have no idea what species of spruce these photos represent is because I didn't care to be honest. The trunk characteristics of this tree are far too interesting to care which species it is :) It's either a red, white or black spruce. Black seems unusual due to the height and the general shape of the tree, but white spruces usually have much larger cones than this one has. Red spruce has very different bark...

If you would like to know more about a bunch of different species of spruce, you can learn about the Norway spruce HERE, the Colorado blue spruce HERE, and the black spruce HERE.

So what's so exciting about this tree? This tree has managed to graft itself, then lose one of the scions (the portion of the plant above the grafted location) so that it looks like an upsidedown-Y tree. Normally grafted trees are no big deal. In fact, there are so many grafted trees sold in nurseries unless you really knew what you were looking for you would never notice the difference. A lot of fruit trees, especially those in the rose family (like apples, pears, plums, cherries, peaches, etc.) are grafted because their root stock isn't very hardy. Since the top of the tree essentially "dies" during the winter then is miraculously "revived" in the spring, obviously some part of the tree stays active all winter in order to perform basic maintenance on the above-ground tissues. That's actually the main reason why cryogenically preserving humans can't work yet: when you freeze our bodies, we actually...freeze. Ice forms in our cells, rupturing the membranes. Because our tissues are frozen solid you don't notice. But as soon as the body starts to thaw, the frozen tissue turns to mush and ends up going necrotic (turning black). Bananas do the same thing; that's why a thawed banana isn't a pretty banana! But great for making banana cream pie...but I digress.

Back to roots. Roots stay alive all winter, and the microbial symbioses between tree roots and the microorganisms that live in the soil can actually generate enough heat to melt permafrost in the arctic! That's an impressive amount of heat. The problem is getting the right amount of these symbioses to maintain a ground temperature above freezing so you can heat the rest of the tree by flowing warm water through the vascular system to prevent the tree from freezing solid. Some trees are better at this than others, hence why some trees are winter-tolerant while others are killed when the ground starts to freeze. Members in the rose family have their roots frozen quite easily, so how can we have apple orchards in Ontario? The ground freezes here every winter. The secret is in the grafting process. The scion of the graft is the apple part, while the rootstock is the tolerant of freezing part. The most common trees to use for rootstocks are also "water scavengers" during times of drought; if you've ever had a willow tree in your back yard and have been unfortunate enough to have a sewer running anywhere in the vicinity, you might be aware of what I mean by a "water scavenger". Willow trees are notorious for their ability to break through concrete and colonize sewers with roots in order to absorb more water. What better way to find a water source (unless you're a homeowner...)?! If you want a nice apple orchard that produces juicy apples, putting your apple scions on willow rootstocks seems like a no-brainer and that is how we "make" apple trees. We don't grow them from seeds at all!

So what does this have to do with these spruce trees? Well, usually when you do a graft you start with one scion and one rootstock and you get one plant. If you start with two scions and two rootstocks you get two plants. Three of each? Three plants. These trees, however, fused together then one of the scions was sacrificed, probably by the other one being too "greedy" and taking too many resources during a time of stress. The scion died but the rootstock remained. It should be no surprise that this tree is significantly taller than its neighbours; it has two sets of roots feeding the crown (the top) of the tree! If that's not cool, I don't know what is.

Colorado Blue Spruce

Species name: Picea pungens var. hoopsii

Common name: Hoopsii spruce, Hoopsii Colorado Blue spruce

Location: Ontario

I had wanted to post back-to-back blogs to contrast the difference between spruces and firs, since many people when they're first starting out at plant identification (me included) have a hard time telling them apart. I didn't get a chance to post a blog yesterday and I had a different blog planned for today, so I guess I'll just have to post two blogs today :)

The Colorado spruce, as I'm sure you can guess, is native to the alpine regions of Colorado in the United States. It has been transported all around the world by humans, favoured for its blueish tint to the needles at the tips of the branches. As the branch grows and the needles age, they lose their waxy frosting that gives them the blue tint, and turn green. The Colorado spruce is very intolerant to shade, and so the needles on the inside of the tree are shed as they become too shaded by branches above them. While the Colorado spruce is a popular Christmas tree, all spruces lose their needles when the tree dries out, so they can be very messy by the time it's time to compost the tree. The needles compared to fir trees, which don't lose their needles when dry, are also much sharper and not as nice to handle, and can be quite dangerous to small children with sensitive skin and to animals (compare the photos of the needles above to the needles in my blog post about the white fir HERE). Spruces also don't smell as wonderful as fir trees do; the typical "Christmas smell" that I think of when I think of Christmas is cinnamon, apples, the smell of fir trees, and a roasting turkey. Yum!

This variety of spruce tree is actually quite misleading when it comes to the "typical" form of spruces. It actually looks absolutely nothing like a typical Colorado spruce, and actually much more like a black spruce (which you can read all about HERE). Black spruces, except when young, have this type of characteristic shape; very dense branch growth towards the top of the tree that point almost straight outwards but with very short branches, then the longer branches towards the bottom of the tree are much longer, droop downwards, and are much more sparse compared to the top of the tree. The Colorado spruce, on the other hand, should be shaped almost like a pyramid with very dense branches throughout the length of the tree, and branches pointing nearly straight outwards. The Hoopsii spruce, a variety of the Colorado spruce, was selected by humans to have that drooping, very narrow growth habit.

As for the uses of the Colorado spruce, it is rarely used in the lumber or paper and pulp industry unless it is found growing in a stand of trees intended for pulping. It grows incredibly slowly and adds very little girth with each growing season, so is not very useful for lumber. The Navajo use the bark from the Colorado spruce as a medicinal item; it is steeped like a tea with other herbs to treat various medical conditions. The Colorado spruce is also the state tree of Utah and (of course) Colorado.

Spindly Black Spruce

Species name: Picea mariana (formerly Picea nigra)

Common name: Black spruce

Location: Nova Scotia

I took this photo in Kejimkujik National Park on the bog boardwalk leading out to the beach. It was a pretty typical maritime spring day: cool in the morning, warming up quickly and becoming incredibly foggy then the fog burning off by the mid-afternoon. This was one of those rare moments where you could see more than 10 feet in front of your face as a fog cloud was blown out of the way.

Black spruce is a typical plant of the boreal forest in Canada and Alaska. It's a native evergreen tree with a very typical shape: somewhat bushy at the bottom, becoming much narrower and more spindly towards the top. One of the most impressive characteristics of this plant towards the northern part of its range is that its a great indicator of predominant wind direction. Black spruce grows very slowly, and slower still when the wind is pushing against the tips of branches. The "wind side" of the tree has much shorter branches compared to the "sheltered side".

Black spruce is one of the many boreal species that require fire in order for their seeds to germinate in great numbers, and so for that reason this species is especially successful at recolonizing the boreal forest after a fire. Since forest fires are relatively common in this forest zone, stands of boreal forest that are dominated by black spruce are often trees of the same age (as opposed to typical successional forests where there are old and young trees of the same species in the same location). Within the boreal zone, it's an incredibly common tree and is at no risk of becoming a threatened or endangered speices.

Black spruce trees grow slowly and never attain a very large circumference despite the tree's age. For this reason they are not valuable lumber trees in the construction business. They are, however, a major source of pulp for the paper industry in Canada. As cultural importance, the black spruce is the provincial tree of Newfoundland and Labrador in Canada.