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Plant Talk: Know Your Christmas Trees/Conifers, Part 1

susan5383

Updated: Jan 21

For good reason, most of the trees we associate with Christmas in the northern hemisphere are evergreens, and also conifers (cone-bearing). Conifers are a large group of trees and shrubs within a main division of seed-bearing plants, the Gymnosperms, in which the seeds are not enclosed within a protective covering. This is in contrast to the second main division, the Angiosperms, or flowering plants,. in which the seed is enclosed in a fruit of some sort. In gymnosperms the seeds are attached to scales which are spirally arranged in a woody or fleshy structure commonly referred to as a cone. 


Not all conifers are evergreen. Exceptions in North America are the larches (Larix spp.) in the pine family (Pinaceae), as well as the dawn redwood (Metasequoia glyptostroboides), native to China but widely planted, and the bald-cypress (Taxodium distichum), of the eastern U.S., both in the cypress family (Cupressaceae). These trees lose all their leaves in autumn and generate a new crop the following season. Conversely, many angiosperm plants are evergreen, the European holly (Ilex aquifolium) being an example of an evergreen angiosperm that is also associated with Christmas.


Conifers are remarkable trees, and there is a lot of information online for anyone who wishes to know more about them. In this article, and a second (shorter) one to be featured in a future issue of Wildflower News, we will cover those conifer species encountered in Alberta. Our discussion includes native species as well as those commonly planted here by the landscape industry. Travellers to other parts of Canada will encounter several more species than are featured in these two articles.  


Adaptation to cold, dry climates and terrain


Conifers dominate large areas as forests in the colder regions of the earth, to which they have some special adaptations. They have narrower water-conducting vessels (tracheids) than angiosperm trees, which means that air-bubbles inside them (formed during drought or freezing) remain small and easily dissolve to allow water movement. This renders conifers more resistant to both cold and drought. Their small leaves allow water droplets (from rain or fog) to coalesce easily to form larger droplets, which fall off and water the tree. Because the leaves of most conifers remain on the tree during winter, they can begin photosynthesis early in the spring. Although their water-conducting system does not allow for the rapid growth possible in angiosperms, slow growth and retention of nutrients in evergreen leaves permits survival in poor, infertile soils. Their roots form a close association with fungi in the soil (ectomycorrhizae) which enables them to better absorb water and nutrients.


Reproduction


Most conifers reproduce by seed, but some, especially the spruces, can reproduce vegetatively by layering, whereby low branches in contact with the ground develop roots and upright shoots. Male (pollen) and female (seed) cones are produced on the twigs, usually both types on the same tree. Pollination is by wind, and pollen is produced in copious amounts: the waves of yellow pollen washed up along gutters in the city or around pools in the forest are a common sight in the spring. Seed cones are made up of spirally arranged, overlapping scales, which usually become woody as they mature (exceptions are the junipers) and bear two winged seeds on their inner sides. The scales, which are tightly closed during seed development but open to allow pollination and seed release, are subtended by papery bracts, which may be short or long, and are useful in identification. Seedlings look like little palm trees with their several linear seed-leaves (cotyledons) at the top of a stalk. 


Conifers are known for their production of pleasant aromatic resins, which serve to protect the tree against attacks by insects and fungi and are also exuded in large amounts after wounding.


Identifying conifers


Autumn colours of tamarack (yellow) with black spruce, in Wagner Natural Area, 1982-10-01. Photo: J.D. Johnson.
Autumn colours of tamarack (yellow) with black spruce, in Wagner Natural Area, 1982-10-01. Photo: J.D. Johnson.

We have relatively few species of conifer in Alberta, and only somewhat more in Canada as a whole, yet many people do not bother to distinguish between them, often referring to them all as “firs” or “pines.”  Apart from the sheer fun of it, knowing the difference between a fir, spruce or pine could help you make a better choice of festive tree at Christmas time. 


With few other plant distractions, winter in the north can be a good time to identify conifers. In the Edmonton area, three species of conifer (white and black spruce, and tamarack) grow in Wagner Natural Area.  Just south of there, populations of jack pine occur on the Devon sand dune, along with tamarack in the associated wetland hollows. 


To be fair, despite lack of native diversity, conifers can be confusing, because of natural similarities, because the same common names have been misleadingly applied to different species, and because species introduced for landscaping and forestry have increased the number and complexity of species on the landscape.  Nor does it help when the nursery trade refuses to use Latin names and, for example, refers to false cedars or arborvitae (Thuja species, in the Cupressaceae) with made-up names like “pine-cedars.” The name “cedar” in North America, whether hyphenated or otherwise, can refer to trees variously in the genera Juniperus, Thuja or Callitropsis (see the conifer list). True cedars of the eastern world are the genus Cedrus and are actually in the pine family.  


A famous Canadian example of name confusion lies in the naming of the Cypress Hills, a region of uplands spanning southern Alberta and Saskatchewan. They are actually an outlying habitat for lodgepole pines but were so-called because the Métis name for pine was translated into French as “cyprès.”


Even taxonomists can be confused. The Douglas-fir (note the hyphen because it is not a true fir) is another example. Before the genus Pseudotsuga (meaning “false hemlock”) was created in 1867, the Douglas-fir (Pseudotsuga menziesii) had been variously considered a pine, a hemlock and a fir. Modern genealogical analysis has indicated that it is more closely related to larches, and a little more distantly related to pines, than to firs. 


Cupressaceae (cypress family)


Members of the Cupressaceae are characterized by scale leaves: small, flat, triangular leaves that are closely appressed to the stems. Our cypress family members, the junipers and the false cedars/arborvitae/Thuja species, are characterized by their scale leaves, although young shoots and new growth have needle leaves, or elongated versions of scale leaves.  The exception is common juniper (Juniperus communis), a low spreading shrub, which has needle leaves only. Our Alberta junipers consist of common juniper, creeping juniper (Juniperus horizontalis), also a prostrate shrub much used in landscaping, and Rocky Mountain juniper (Juniperus scopulorum), a medium-sized shrub to small tree.


All of the native junipers have small, round, fleshy cones, blue with a whitish bloom, looking more like berries than cones. Distribution of all three species is concentrated in the mountains, although common juniper does also occur locally. Rocky Mountain juniper has been planted, for example, at Hermitage Park, where it regularly attracts birds, such Townsend’s Solitaires, to feed on the “berries” in the winter. 


  1. Branch of common juniper (Juniperus communis) showling needles in whorls of three, sharp-pointed, with a broad bank of white stomata on the upper surface, and yellowish pollen catkins in the leaf axiils. The green buds at the end will produce more shoots. Sunwapta Falls, Jasper National Park, 2024-06-23. Photo: P. Cotterill.

  2. Blue, berry-like cones in the leaf axils of common juniper. The cones are made up of three or more fleshy scales which are tightly closed during seed development and contain 1-3 seeds. Jasper townsite, 2011-09-15. Photo: P. Cotterill.

  3. Creeping juniper (Juniperus horizontalis), showing its typical habit as a sprawling shrub. Restoration area at Frank Slide Interpretive Centre, Crowsnest Pass, 2024-08-15. Photo: P. Cotterill.

  4. Creeping juniper showing the scale leaves and seed cones. Kootenay Plains, 2010-06-22. Photo: P. Cotterill.

  5. Hanging branch of Rocky Mountain juniper (Juniperus scopulorum), a planted tree at Hermitage Park, Edmonton, 2021-11-18. Photo: P. Cotterill.


The native western red cedar (Thuja plicata), with scale leaves, is rare in Alberta’s mountains but occurs extensively in B.C. By contrast with the junipers, its ovoid cones, about 1 cm long, become woody and brown. The planted tree most likely to be seen around Edmonton, I believe, is the eastern white cedar (Thuja occidentalis), native to Ontario eastwards and southwards, which is widely used in landscaping and is often referred to as an arborvitae.  


  1. Western red cedar (Thuja plicata) showing scale leaves, pollen cones (red blobs) and narrow-ovoid, erect, immature seed cones. North Thompson River Provincial Park, B.C., 2010-06-10. Photo: P. Cotterill.

  2. Twigs of western red cedar showing scale leaves on flattenened twigs, and mature, open cones after seed shed. Bromley Rock Provincial Park, B.C., 2006-08-01. Photo: P. Cotterill.


Pinaceae (pine family)

Comparison of growth form of pine (left) and spruce growing together in a suburban area of Edmonton, 2024-12-31. Photo: P. Cotterill.
Comparison of growth form of pine (left) and spruce growing together in a suburban area of Edmonton, 2024-12-31. Photo: P. Cotterill.

Recognizing the genera


Moving on to our other major family of conifers, the Pinaceae… In terms of the trees that are likely to be encountered in the Edmonton area, the most important distinction to be made is between a spruce and a pine. It is not difficult. With their shapely pyramidal form and dense, dark green foliage (due to the close-set needles) and intermediate branches between the main branches, spruce present a quite different appearance from the more open form of many pines, in which the trunk is visible between the whorls of branches, and the spaced clusters of longer, bright green needles also contribute to a more open appearance.


Distinguishing between a spruce and a pine is relatively easy but separating a spruce from a fir may be more difficult, as in both the needles are attached singly to the twigs and the form is rather similar. In spruce the needles are four-sided, so can be rolled between finger and thumb, and pointed, often sharply, whereas those of firs are flat and usually rounded at the end, soft to the touch. Another important character is that spruce needles are attached to distinct peg-like projections on the ridged and grooved twigs, while the leaf bases in firs are round and flatter (best seen as leaf scars) on smoother twigs. The cones of spruce fall off the tree intact, so are easily found on the ground, but in firs they disintegrate on the tree, leaving behind a central spike. This means that if cones are needed for identification purposes, they must be looked for on the tree. The bark of firs, at least in younger growth, is grey, noticeably smooth, and dotted with resin blisters. Young bark in spruce can also appear to be smooth and grey, but older bark becomes dark grey and scaly. However, the single easiest way to tell spruce and fir apart is the touch test: grab hold of a young twig and if the tree is a spruce you’ll say “ouch” and withdraw your hand!


Firs (Abies)


In Alberta we have only two species to worry about, and they are best distinguished by their location. Subalpine fir (Abies bifolia, formerly A. lasiocarpa) grows at high elevations in the mountains; balsam fir (Abies balsamea) grows in forest habitats from north-central Alberta eastwards. In the former, the needles curve upwards along the sides of the twig, whereas in balsam fir they spread horizontally so that they appear to be in two horizontal rows or ranks. Subalpine fir has rows of white stomata on both sides of the needle, although predominantly on the under side; in balsam fir they are confined to the lower surface.  Balsam fir has been planted in Edmonton, although it does not seem to be abundant, and is prized as a Christmas tree for its pleasant scent. 


The cones of firs are unusual in that they are erect, and whole cones do not fall from the tree; rather, the cone scales fall off individually, leaving behind the axes, discernible as dark, upright spikes.


  1. Subalpine fir (Abies bifolia) showing upcurving needles on the twigs. Stagleap Provincial Park, B.C., 2024-08-12. Photo: P. Cotterill.

  2. Subalpine fir, showing foliage, immature pollen cones and (purple) erect, young seed cones. Lower down on the left are the brown spikes of old cones that have lost their scales. Ptarmigan Cirque, Kananaskis Country, 2008-07-12. Photo: P. Cotterill.

  3. Balsam fir (Abies balsamea) showing flat, two-ranked, dark green foliage (stomata confined to lower surfaces of needles) with new shoots developing. Coyote Lake Nature Sanctuary, 2023-08-03. Photo: P. Cotterill.


Spruces (Picea)


Engelmann spruce (Picea engelmannii) is likewise only to be found in subalpine or alpine habitats in the mountains, although it can hybridize with white spruce (Picea glauca) where they overlap at somewhat lower elevations. It often grows in combination with subalpine fir, and at open alpine situations in tundra forms the dwarf forests known as krummholz.  The needles are curved and point upwards towards the tip of the twig.


White spruce (Picea glauca) are the trees commonly seen in a range of habitats, naturally forming forests or occurring in mixed stands with deciduous trees, in central to northern Alberta, although towards the south they tend to be confined to the cooler, deep ravines. They are widely planted in urban areas as a landscaping tree.  Besides being ornamental, they offer multiple benefits such as cooling and improving air quality, as well as providing excellent food and shelter for squirrels and birds. Deer use spruce stands for shelter in the winter. 


Colorado spruce (Picea pungens), native to the western U.S., is also widely planted as a stately conifer, easily recognizable by its bluish foliage, which is even more prickly-pointed than that of white spruce (hence its Latin epithet). It has longer pale brown cones (5-12 cm long compared to 3-6 cm in white spruce), with cone scales that are shallowly toothed at the tip, compared to the smooth-edged cone scales of white spruce. 


Norway spruce (Picea abies) is another introduced tree that is planted locally. It can be recognized by its markedly drooping branches and long, cylindrical cones. 


In contrast, black spruce (Picea mariana) is a slender, columnar, sometimes scraggy-looking native tree, lacking a distinct conical form. It can have a cluster of branches and cones at the top of the tree, separated from the lower branches by an expanse of trunk, suggestive of a bird’s nest. It grows naturally on wet, peaty soils in this part of Alberta, and can be seen locally in the treed fens of Wagner Natural Area. White spruce also grows in Wagner, on somewhat higher ground, and this provides a good opportunity to distinguish between the two species. Black spruce has hairy twigs that appear dark, whereas in white spruce they are hairless and somewhat shiny. White spruce has cylindrical, lighter brown cones, papery-flexible scales; in black spruce they are barrel-shaped, 2-3 cm long, woody, and a grey-brown. Take a look at the ground. If white spruce is present there will almost certainly be a few cones lying around; they fall off the tree after the seeds have been released in late summer or the following spring, whereas in black spruce they are retained on the tree for several years. A good idea to confirm black spruce identity is to look for branches on the ground that have been severed by squirrels or wind and bear clusters of the cones.


  1. Engelmann spruce (Picea engelmannii), showing foliage, immature pollen and seed cones. Sunshine Ski Resort, Banff National Park, 2008-07-07. Photo: P. Cotterill.

  2. Healthy young white spruce (Picea glauca) showing vigorous new growth at the edge of a mature mixed spruce and lodgepole pine forest, Athabasca Falls, Jasper National Park, 2024-06-23. Photo: P. Cotterill.

  3. White spruce in Edmonton garden, showing spent pollen cone and developing seed cones, 2010-06-01. Photo: P. Cotterill.

  4. Foliage and mature seed cones of white spruce, Wagner Natural Area, 2005-03-28. Photo: J.D. Johnson.

  5. Pollen cones and characteristic blue foliage of Colorado spruce (Picea pungens) in an Edmonton garden, 2010-05-31. Photo: P. Cotterill.

  6. Norway spruce (Picea abies) in an Edmonton garden, showing characteristic drooping branches, 2024-12-21. Photo: P. Cotterill.

  7. Immature seed cone of Norway spruce, University of Alberta campus, 2022-07-04. Photo: P. Cotterill.

  8. Bark and branches of black spruce (Picea mariana), Wagner Natural Area, 2003-06-11. Photo: P. Cotterill.

  9. Black spruce cones on old, fallen trunk, Wagner Natural Area, 2019-11-01. Photo: P. Cotterill. 


Larches (Larix)


Larches have their needles in groups, like those of pines, although they are shorter and more numerous (in clusters of 10-60, depending on the species). They are deciduous and open from buds on dwarf shoots along the sides of the twigs in spring. Single, spirally arranged leaves also occur on the long, growing shoots. Dwarf shoots produce leaves for several years, accumulating leaf scars as the annual growth falls off in the autumn; their buds can also develop into pollen cones, seed cones and long shoots. A winter twig of larch has a characteristic knobbly appearance due to the leaf shoot bases and buds along its length. 


Of our three Albertan larches, two, western larch (Larix occidentalis), exceedingly rare, and subalpine larch (Larix lyallii), are confined to the southern mountains. In situations where there is a possibility that both mountain species occur, they can be separated on characters of the cones and subalpine larch’s woolly twigs. The third, tamarack (Larix laricina), is a lowland, boreal forest tree, extending as far south in the province as the North Saskatchewan River, and it is by far the commonest. In fact, unlike the western species, it ranges all across Canada from the far northwest, eastwards into the northeastern U.S.


Tamarack can be readily seen in Edmonton area nature reserves, such as Bunchberry Meadows Conservation Area, where it may grow in pure stands in wet, low-lying areas or as a fringe around marshy wetlands. In very wet areas in the fens of Wagner Natural Area, it may grow so slowly that a tree only a few metres tall, branched and gnarled, can be over 200 years old.  Unfortunately, the bark of mature trees is very palatable to porcupines, which cause huge scars and sometimes the death of the tree. In winter, tamarack can be readily distinguished from the black and white spruces with which it often grows because it is bare. In summer its small, bright green leaf clusters give it an overall feathery look in contrast to the dark green spires of the spruces, as does its golden foliage prior to leaf fall. 


Siberian larch (Larix sibirica), native to northern Asia, is frequently planted in Edmonton as a tall, handsome ornamental with spreading branches. 


  1. Subalpine larch (Larix lyallii) newly in leaf at Sunshine Ski Resort, Banff NP, 2008-07-07. Photo: P. Cotterill.

  2. Subalpine larch showing fall colours and old cones. Fortress Mountain, Kananaskis Country, 2006-11-01. Photo: P. Cotterill.

  3. Tamarack (Larix laricina) showing a stunted growth form in a fen in Wagner Natural Area, 2006-06-18. Photo: P. Cotterill.

  4. Tamarack twig with open buds on a dwarf shoot, new leaves and a very immature seed cone. Bunchberry Meadows Conservation Area, 2021-05-01. Photo: P. Cotterill.

  5. Tamarack with foliage and developing seed cones, Tucker Lake, Alberta, 2011-06-18. Photo: P. Cotterill.


Other members of the Pinaceae family


Western hemlock (Tsuga heterophylla) is rare in Alberta but readily encountered in B.C. in moist forests of the eastern and coastal mountains. The leaves are flat and blunt like those of firs, and also two-ranked, but variable in length, giving the twigs a characteristic, delicate look that is easily recognizable once known. The twigs are somewhat rough owing to the tiny remnant leaf bases, but hemlocks cannot be mistaken for spruces. Western hemlock can be recognized from a distance by its leading shoot, which droops to one side. The cones are ovoid, pale brown with few rectangular scales, and blunt-tipped. 


Douglas-fir (only Rocky Mountain Douglas-fir, Pseudotsuga menziesii var. glauca, grows in western Alberta), could be mistaken for a spruce, but its singly attached leaves are flat with a prominent midvein, and on very short stalks rather than peg-like projections. They are arranged all round the twig (or sometimes somewhat two-ranked). The cones are their distinctive feature, almost always allowing identification because they fall intact to the ground once the seeds have been released each year. They have very long, three-pointed bracts that in the Rocky Mountain variety of Douglas-fir are bent back. The species is planted in the Edmonton area. 


  1. Western hemlock (Tsuga heterophylla) sapling, showing bent leader. Mount Rainier National Park, Wash., 2006-08-05. Photo: P. Cotterill.

  2. Foliage and new growth of western hemlock, Strathcona Provincial Park, B.C., 2010-06-16. Photo: P. Cotterill. 

  3. Foliage of Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca), Valley of the Five Lakes, Jasper National Park, 2024-06-24. Photo: P. Cotterill.

  4. Seed cone of Rocky Mountain Douglas-fir, showing the three-pronged bracts. Valley of the Five Lakes, Jasper National Park, 2024-06-24. Photo: P. Cotterill.



Our native and introduced trees that belong to the large genus of pines (Pinus) will be briefly described in the second part of this article in the next Wildflower News.


For a comprehensive list of conifers that can be found in Alberta (both native and those used in the landscape industry), interested readers are directed to the following article on our website:


Reference: 

Farrar, John Laird. 1995. Trees in Canada. Ontario. Fitzhenry & Whiteside Ltd. & Canadian Forest Service. 


A useful identification key can be accessed at: https://tidcf.nrcan.gc.ca/en/trees/identification/conifers




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