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Winter Dendrology: The Study of Trees

Most of us learned about trees in elementary school. We learned how to identify them mainly by the shape of their leaves and on occasion, some teachers would talk about the bark of the tree. Well, last Sunday we had an in-field workshop, led by Bob Bowles. Bob taught us there are many other ways to identify trees, especially this time of year before leaf out.

Workshop Participants and Bob: On their way to the field to learn about trees.

Working through the tree identification keys.

Tree location is an important factor in identifying the species. Certain trees will only grow in uplands, whereas other trees will only do well in wetlands or lowlands.

Bob also used a Tree Identification Key. The key is used to make it easier and quicker to identify the tree or shrub. It takes a little time to become familiar with using the key, but once you know what you are doing the key becomes an invaluable tool.

Next, we discussed deciduous and coniferous trees. Deciduous trees shed their leaves during the fall season, like poplar, birch, ash, maple and oak, just to name a few. There are over 100 deciduous species of native trees in Canada; 84 species are native to Ontario. Coniferous trees keep most of their needles during the winter months, such as spruce, pine, balsam fir and cedar. There are about 30 coniferous species native to Canada; 20 species native to Ontario.

Bob talked about the bud arrangement, whether the buds were opposite each other or alternate. He also spoke about the terminal buds, lateral buds, leaf scar and bud scales.

Outfitted with all this new knowledge, a small group of us headed into the forest and the wetlands to begin identifying trees.

Our first tree was a precocious pussy willow (Salix discolour). This species grows only in a wetland area.

Pussy Willow: Alternating flowers

This willow tree is one of 14 species in Ontario and the catkins were in full bloom. We learned there are male and female willow trees. The pussy willow we observed was male. We discovered that the buds and branches alternate from each other and have only 1 scale. Most trees have 2-6 scales. The bud scales are structures that are modified leaves covering the bud during the winter dormancy.

Our next tree was white ash. This is an upland tree and we learned the twigs and branches are opposite to each other. Bob gave us the mnemonic MAD. M for maples, A for ash and D for Dogwood.

White Ash Tree: Opposite Branches

Maple, ash and dogwood trees have opposite branches. Now when you see a tree during the winter or early spring with opposite branches you will know it has to be a maple, ash or dogwood.

We went further into the wetland and discovered the differences between white ash, black ash and green ash. Black ash will only grow in wetlands and green ash is an in-between tree doing well where the land transitions from upland to lowland. White ash, as mentioned is an upland tree with "C" shaped scars while the black ash, a wetland tree, has "D" shaped scars. A scar is left on the twig when the leaf falls off. Another way of identifying ash trees.

Beech Tree: Holds some of its leaves throughout winter

Beech Tree: Buds

Photo Credits: June Crinnion

We are excited to continue learning new skills in identifying trees and shrubs. Our next workshop is on Sunday, April 24th from 1:00 - 3:00 PM. If you are interested in getting to know trees and being able to identify them this is the workshop for you. Just send us an email to register.

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