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The Green pages

Glossary – Trees and shrubs

Paper birch (Betula papyrifera)
Photo: Jardin botanique de Montréal (Gilles Murray)
Betula papyrifera.

Branch bark ridge and branch collar

If you look carefully, you will see that where the branch meets the trunk there is an elongated, wrinkled area, called the branch bark ridge. At the base and on the sides of the branch is a swelling, varying in size depending on the tree species, called the branch collar. The collar is formed of growing tissues that will help the cut to seal over.


Puddling involves dipping the roots of a bare root plant in a mixture of water and soil immediately before planting. This helps prevent the roots from drying out and places them in immediate contact with the soil, allowing the plant to root more easily in its new site.

Root-bound trees and shrubs

Plants that have been grown for a long time in containers (especially plastic ones) often become root bound – when the roots can’t grow outwards, they start to coil around themselves in the pot. If a plant is placed in the ground in this condition, the roots could eventually strangle the collar and kill the plant. If your plant is root bound, it is a good idea to make vertical cuts about 2 to 5 cm deep in 4 or 5 spots around the root ball before planting it. The cuts will stop the spiral growth and encourage the new roots to spread out sideways.

Testing your soil

To determine what quantities of amendments and fertilizer you need to add, it is a good idea to have your soil tested. A laboratory analysis will tell you what type of soil you have (sandy, clay, silty), its pH, some of its nutrient content, its percentage of organic matter, and how you can improve it. This service is available at most garden centres and you should be given recommendations along with your test results.


Cut base of a branch projecting from a tree trunk.


Vigorous shoot growing more or less vertically from the base of a tree or above a graft point, often after the tree is pruned.

Water sprouts

A water sprout is a vigorous upright shoot rising from the trunk or branches. Water sprouts compete with neighbouring branches. They are also weakly anchored and vulnarable to wind and ice damage. Over-pruning encourages heavy growth of water sprouts.


Trees and shrubs seal their wounds by producing woundwood, also called callus tissue, which starts forming around the cut and grows inward to cover it. The woundwood is produced by the remaining live cambium around the cut. If any of the cambium is destroyed, the wound cannot seal over completely. The cambium is a thin layer of dividing cells under the bark. It is what causes the trunk and branches to grow in diameter.

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