One of the keys to understanding a subject better is understanding tree terminology used surrounding it, and trees are no exception. As arborists, we often visit properties to provide quotes and to speak with Toronto homeowners about their trees– this can present an opportunity for learning, and as passionate tree educators, we are happy to engage. So what are the essential terms to know as a homeowner in Toronto, so you can adequately communicate about and care for your trees? This article will attempt to list them here for you and explain them in terms that are easy to understand, identify, and apply.
Trunk
The tree’s trunk is the central woody stem or axis of a tree. It is a key feature distinguishing trees from other plant life. It is composed of several parts including the outer bark, cambium, sapwood, and heartwood. The trunk provides structural support as well as being the central vascular system through which water and nutrients exchange through the roots, to the leaves and back.
Limb
A limb refers to the part of a tree that emanates from the trunk– this term can be interchangeable with branch.
Primary Branch
A primary branch is a branch that comes directly off the trunk
Secondary Branch
A secondary branch is a branch that comes directly off a primary branch
Tertiary Branch
A tertiary branch is a branch that comes off a secondary branch. This is the outskirts of a tree generally speaking, and is where an arborist does the “healthy” work of maintenance but no major pruning cuts
Canopy
A tree canopy is the layer of leaves, branches, and stems that cover the ground when viewed from above. These canopies are essential to Toronto homes, cooling the area and ground beneath them in the summer, reducing gaseous and particulate pollution, and providing food and shelter for local urban wildlife such as squirrels, birds, and racoons. May also be referred to as the “crown”.
Roots
Tree’s roots are its underground organs that anchor the tree to the soil while also absorbing water and nutrients helping the tree to live, grow, and repair itself. This guide helps Toronto homeowners master the basics, enabling them to care for and discuss their trees effectively.
Deciduous
Examples of deciduous trees would be Maple, Oak, anything that defoliates (loses its leaves) during colder months (note: some of Toronto’s deciduous trees, if planted in southern climates, would not lose their leaves). These trees generally have a shorter but faster growing season and are part of our beautiful fall landscapes.
Coniferous
These sometimes prickly, hearty trees grow all year round but slow down during winter months. They respond to pruning differently than deciduous trees and thus require a different approach to caring and maintaining. Because these trees grow evenly all over (not only spreading out to the tips) they can also be shaped into hedges more easily than most deciduous trees.
Epicormic Growth
Epicormic growth is growth that comes out of the living tissue of a tree and only sprouts during times of stress. It is basically an insurance policy for the tree.
Suckers
Suckering is a response of new growth to some sort of stressful situation. The location of the suckers can be an indicator of the type of stress the tree is experiencing, for example suckering from the base of the tree can often happen when your canopy is dying back heavily or the tree is in full senescence.
Decay
Every tree has specific pests and is susceptible to various diseases, but all that aside, general decay is the natural course for a tree. Hypothetically if a tree was never wounded or lost a limb in its life it may not experience decay or rot, but that is almost entirely impossible.
“Healing” or Sealing
We heal a scar, trees seal them. Let’s say a branch rotted off, there will now be a hollow where the branch used to attach to the main trunk. It goes about over many years sealing over from the outside and within, like an orb. Wildlife will often take advantage and inhabit these orbs.
Compartmentalization
Compartmentalization occurs in all aspects of a tree’s biology. It effectively means it can use any living part of itself to continue growing from. This also refers to the process of sealing wounds on the cellular level in compartmentalizing decay within the tree structure not seen on the surface. So even after a catastrophic structural failure, if there remain any small healthy branches, the tree will push the resources and stored energy through that remaining branch and you’ll see an enormous response of growth and the regeneration of a new canopy.
Cambium
Cambium is like a sheet of paper that wraps around the entirety of the tree just below the bark, this comprises all of the living cells of the organism that is a tree. After a certain number of years this turns into inert wood (non-living tissue, what we use as lumber). The cambium is made up of phloem which sends sugars from the leaves down the trunk into the roots and xylem which sends water up from the roots to the leaves. Anything that cuts deeper then the bark into the living tissue damages these systems for the tree.
Burl
A burl is a cluster of buds that for unknown reasons do not break through to the surface to become branches. They do not negatively affect the health of the tree, nor are they an indicator of stress. Some species are more prone than others, for example the Willow.
Senescence
Senescence is the process of biological aging, where cells stop dividing but don’t die, and organisms gradually lose functional characteristics. This leads to an eventual weakening/exposure for a tree and eventual “death”, typically the result of a combination of age, decay, wounds, and disease. After which the mature tree will begin to regenerate from new sprouts either from the base or along its trunk and begin anew.
It is our hope that with help you understand tree terminology so you can also better understand the needs and life cycle of your trees. It’s important to know what to look for to ensure we are mitigating risk early, maintaining a tree in optimal health and doing all we can to provide the right environment for the tree to thrive in. Caring for the trees on your property as a Toronto homeowner in an urban landscape can be tricky– that’s why the arborist team at Heritage Tree Care is available year-round for consultations and quotes! We will meet you on your property to discuss your tree care needs, no charge. We are your partners in tree health and longevity!