Trees are an essential part of life in any city—offering environmental, ecological, economic, and social benefits every day. With more than 380,000 publicly owned trees lining Edmonton’s boulevards, parks, and sidewalks, our urban forest is a living, growing community asset that adds beauty, shade, cleaner air, and a sense of connection to nature. All these benefits are formally recognised in the literature as ‘ecosystem services’, and their value is so great that scientists and officials consistently struggle to put a monetary value on them.
We hope this walk encourages you to slow down, look up, and get to know the incredible trees growing right here in our own neighbourhood!
When faced with an unknown, the largest and most obvious characteristics of the plant are compared with an alternative; for example: does the plant have broad leaves or does it have either scales or structures resembling needles? Here we can choose one of these two paths. This is called dichotomy, and a plant key arranged in this manner is called a dichotomous key. We can continue down this path of 2-branch decision-making with finer and finer details until we arrive at an unequivocal result (easier said than done!). This is the method used by academics in the field. For very similar species, a very fine detail of some minute reproductive part may need to be used as the distinctive feature.
Another way to identify plants is to simply have a list of known plants in an area along with their descriptions, usually accompanied by pictures or drawings and organized in broad categories (for example by flower colour). This is a more informal method and it is frequently used by many plant guides available for a specific region.
In non-academic settings, there is no reason not to use the more informal method which may also be combined with some form of less rigorous dichotomous key.
Technological aids such as AI can be used these days to identify plants from photos, but the results should always be confirmed by a more rigorous method.
Plants have common names that are informal, for example ‘red elderberry’. Plants also have formal names, called either the scientific name, Latin name, or binomial name. This name has two terms which are the genus (plural: genera) and the species, for example Sambucus racemosa (red elderberry). The genus is always capitalised, the species is never capitalised. The scientific name is always written in italics.
Like animals, plant species may be distantly related (like humans and mice) or closely related (like humans and chimps). Two species sharing the same genus are closely related, for example Picea glauca (white spruce) and Picea pungens (blue spruce). In fact, two species sharing the same genus will belong to the same family. A plant family may have different genera, for example the family Pinaceae will contain the genera Pinus (the pines) and Picea (the spruces), as well as others. This is useful when we need to classify plants. The scientific study of these relationships is called systematics.
Most land plants have leaves, but some have “true leaves” and some have “fronds” (the ferns). Of the plants with true leaves, many have flowers, but some do not. The group that has flowers, we can call ‘flowering plants’. Of the plants that have true leaves but no flowers, most have seed cones, and we can call this group the ‘conifers’. In an urban environment, we will mostly be dealing with conspicuous plants that are either conifers or flowering plants.
Conifers have seed cones that can remain in the plant for years, and their leaves tend to resemble long needles, short needles, or even scales. They are always woody. They may be trees or have more bushy forms. They are usually (but not always) evergreen, maintaining their leaves through the winter.
Flowering plants have flowers at some point in the season, and then they bear fruit. As a loose generalisation, their leaves tend to be broad. In high latitudes they are almost always deciduous, losing their leaves before winter (with some notable exceptions).
In high latitudes with harsh winters, it becomes increasingly difficult to support big trees. The number of native tree species in our area is fairly low compared to other regions. Many of these species are not well suited to urban environments. Much of the planted urban tree species population is composed of non-native (introduced) species.
Many species are valued as ornamentals and plant breeders will produce different varieties of a species either through selection of natural variation or through cross-breeding with compatible species. These varieties may differ significantly from the wild form. Sometimes these varieties have commercial names given by the breeder, but they can also have scientific names if they have been cataloged, and this will include a third component to the name indicating variety or cultivar form.
One can also find scientific names with a multiplication sign such as Tilia ⨉ flavescens. This indicates that the species is a hybrid, but it is not always stated which two species were the original parents, and the name can also apply to other crosses of the first hybrid.
It is very common in an urban environment to find cultivated forms and hybrids of native plants as well as introduced species. Examples of widely cultivated forms of native species in our area include meadowsweet and dogwood.
To keep the walk a manageable length (in both distance and time!), we are focusing on trees first and bushes second; then some relevant herbaceous species will appear here and there. Below is a list of species we will encounter, ordered by the scientific family name.
Red elderberry (Sambucus racemosa)Native to Alberta with opposite compound leaves; very small flowers in fairly large racemes that bear many small red fruit
Wormwood (Artemisia absinthium)Non-native species, cultivated as ornamental and to make absinthe; Alberta has many species of Artemisia throughout the province
Paper birch (Betula papyrifera)Native range in Alberta and widespread in the river valley, also cultivated as an ornamental
Western snowberry (Symphoricarpos occidentalis)Native to Alberta, two species of snowberry in the river valley, sometimes cultivated as an ornamental
Ground juniper (Juniperus communis)Native range in Alberta, widespread in the mountains, commonly cultivated as ornamental and groundcover; many varieties
Western red cedar (Thuja plicata)Very little range in Alberta, widespread west of the Rockies; not sufficiently hardy for Edmonton but it can be cultivated with some effort
Wolf willow (Elaeagnus commutata)Native to Alberta but not usually cultivated; another Elaeagnus that was introduced and widely cultivated in Edmonton is ‘Russian olive’
Caragana (Caragana arborescens)Introduced as an ornamental and it quickly escaped into the river valley; very aggressive competitor
Bur oak (Quercus macrocarpa)Prized urban tree but very low success rate in these latitudes; the only oak that is barely hardy enough for sub-boreal climates; the only tree of the bunch that bears a true nut
American linden (Tilia americana)Non-native range but successfully cultivated; a great choice for parks and grounds in general; very fragrant when flowering and the dried flowers make a calming tea; the leaves are somewhat heart-shaped and asymmetric at the base
Green ash (Fraxinus pennsylvanica)Medium size tree with an attractive crown and bright yellow leaves in autumn; these latitudes push the limits of this species that flushes late and drops leaves early; distinctive compound opposite leaves
Japanese tree lilac (Syringa reticulata)An Asian lilac that often takes the shape of a small tree, usually with white flowers
Common lilac (Syringa vulgaris)More bushy lilac with fragrant pink to purple flowers or white flowers
Pines have long needles in bundles of 2 or more (very rarely singles), the needles are triangular or hemispherical in cross section, and much longer than 2 cm in normal growing conditions. Spruces have solitary needles typically all around the branches, the needles are 4-sided and typically shorter than 2 cm; they tend to be pointy but some are more prickly than others
A major way to begin pine classification is to look at the number of needles in a bundle. All of these pines listed below have 2 needles per bundle, occasionaly 3.
White spruce (Picea glauca)One of 3 native spruces in Alberta, typical conical shape and one of the dominant conifers in the area, which is also planted as an urban tree or in tree stands in parks; the needles are short, pointy, and four-sided; the needles roll easily between the fingers
Blue spruce (Picea pungens)A spruce with a more southern range; the needles can have a definite blue hue depending on variety; it is widely cultivated as a large ornamental and it is the preferred spruce for spruce tip tea; the cones are much larger than the native spruces
Lodgepole pine (Pinus contorta)Native in the area, but more dominant in the foothills and more rainy mountains of the Grande Prairie region; it is prized for the straight main trunk as a source of lumber
Mugo pine (Pinus mugo)Imported ornamental with compact growth habit; it can take on a small tree shape if not properly pruned; with strategic pruning it can be kept in a very compact bushy form
Austrian pine (Pinus nigra)Occasionally planted as an ornamental in Edmonton; attractive dark green and long, thick needles
Ponderosa pine (Pinus ponderosa)Rare in Alberta; the native range is west of the Rockies; a very valuable lumber species
Scots pine (Pinus sylvestris)Imported from Europe; it has a very interesting orange bark with irregular patches of different shades; fairly easy to grow and maintain; a staple of the urban park landscape
A common family in Alberta with many representative species.
Saskatoon berry (Amelanchier alnifolia)Big bush to small native tree, easy to find in the river valley but less commonly used as an ornamental (a shame); showy white flowers and edible fruit; the leaves are slighlty oval with more prominent serrations toward the tip and a smooth margin towards the petiole
Shiny cotoneaster (Cotoneaster lucidus)An introduced hedge that has naturalized in some areas of the river valley; bright yellow and orange and red leaf tones in the fall; underside of leaves is tomentose; tiny brown spots are visible on the top surface of the leaves
Crabapples (Malus sp.)All species are introduced; a great number of varieties can be seen; small trees with greyish and rather smooth bark that are prolific flower producers; the fruit can be edible with caution as the seeds can contain cyanide; leaves soft with medium size serrations and an acute tip
Amur cherry (Prunus maackii)Non-native cherry with various leaf colors from green to deep red depending on variety; small size tree with showy flowers but less prolific than the apples in this area; cherries and crabapples have similar looking leaves with serrations and an acute tip
Pin cherry (Prunus pensylvanica)A native cherry that is less common than chokecherry and very rarely planted as an ornamental; less prolific flowering than chokecherry; fruit bright red, edible but astringent; bright green foliage; petioles glandular
Chokecherry (Prunus virginiana)Native cherry that is widespread in the river valley and planted as an onamental; dark, almost black fruit that is edible but very astringent; fragrant flowers in racemes; petioles not glandular
Wild rose (Rosa sp.)Provincial flower; not widely planted as ornamental as cultivated imported varieties are preferred; found everywhere in the river valley; flowers very showy but short-lived; fruit is edible with caution because of irritating hairs inside; flower petals also edible as are the garden varieties
Rowan (Sorbus aucuparia)European verion of the native mountain ash; occasionally escaping into the river valley; bright red-orange fruit that persists during winter
Mountain ash (Sorbus scopulina)Native tree or bush of smaller stature than rowan; prolific fruit producer; bright red to orange fruit in pendulous corymbs that persist through the winter and give a colourful contrast in the snow; fruit is a favourite food of the bohemian waxwing
Meadowsweet (Spiraea alba)Native small bush usually with white flowers; many cultivated varieties have been developed; not commonly found in the river valley in the city as it prefers wet meadows and shores
Popplars and willows are quintessential Alberta species. There are close to 50 species of willows in Alberta, sometimes very hard to distinguish. Poplars are less diverse with 5 species, but they dominate many ecosystems. It is very common to find mixed woods in the river valley, composed of poplar, spruce, and birch as the main trees.
Balsam poplar (Populus balsamifera)Large tree with very shiny leaves and a distinctive aromatic resin that covers leaf buds and young stems; widespread in the river valley and sometimes planted but rarely as an ornamental or city tree, probably due to higher water requirements; it is more frequently planted as barrier or in parks; this tree is the main offender for the fluff that floats around in June
Trembling aspen (Populus tremuloides)A dominant native species in our area, medium size tree, usually smaller than balsam poplar; the leaves are somewhat triangular with petioles that are flattened horizontally; wind causes the flattened petioles to move from side to side but not up and down, resulting in a characteristic trembling of the foliage which gives the species its name; much of the cultivated ornamentals are the columnar variety which is caused by a single gene mutation
Manitoba maple (Acer negundo)Possibly native to Alberta, very widely planted; the only maple with compound leaves; flowers of different sexes on different individuals; opposite leaves; a medium size tree that can sometimes get quite large; main stem quick to branch near the base; the fruit is a typical disamara which are two winged dry fruits that are joined on one side
American elm (Ulmus americana)Non-native tree but one of the main urban trees in Edmonton; grows quite large even with hard winters, and it has a distinctive umbrella-shaped crowns that tower over streets forming tree tunnels that are prized in mature neighbourhoods; the leaves are very distinctively asymmetric at the base and have toothed margins and an acute tip; until recently Edmonton served as a reservoir for elm trees free of Dutch-elm disease but this is no longer the case
European elm (Ulmus pumila)Smaller tree than the American elm in these latitudes, sometimes with a more bushy structure; the leaves have the same features as American elm but much smaller in size