Module 1 Glossary


When a substance, such as water, is attracted to, or sticks to something else.


Discolored and depressed bark that is dead.

Capillary Action

The process where one water molecule lifts itself up slightly to adhere to the inside of a small tube, or in a plant's case the stem and leaves, and the water molecules below lift themselves up to cohere to the initial water molecule.


A cylindrical and fuzzy collection of seeds that carry either the male or female reproduction organ for plants.


A photosynthetic pigment that helps convert sunlight energy to chemical energy, like sugar.


A tree that sends out individual stems from its roots to which other trees grow from and become clones.


When a substance, such as water, is attracted to, or sticks to itself.


Refers to something composed of two or more elements.


A process in the water cycle when water vapor rises in the atmosphere, it cools off as it passes through air with cooler and cooler temperatures. As the water vapour cools, it changes from gas to liquid and the condensing water vapour forms tiny water droplets that make up clouds.

Coniferous Tree

Trees that have needles instead of leaves (such as pine trees).

Deciduous Tree

Trees that have leaves that change colour and fall off in the autumn season (such as the trembling aspen).


When there is a lack of leaves over small or large areas of the tree during warmer seasons.


A plant (or animal) that has a male and female reproductive organ.


In terms of TREE, discolouration refers to when the trembling aspen bark turns any colour other than a pale green or white.

Early Wood

The lightly coloured, less dense wood that is created by initial rapid growth when the vascular cambium layer rapidly divides.


The simplest substances found in the world and that make up all matter.


The innermost layer of the cells, found in roots of trees. These cells are made of thick cell walls. This layer serves to regulate water and nutrient movement between the soil and the vascular tissue.


The outer layer of tissue in a plant.


During the water cycle, this step is when the sun heats up bodies of water, and the water changes from liquid to gas.


Tissue in a root that is right underneath the epidermis layer. The exodermis replaces epidermis tissue as it wears away and dies off.

Foul Smell

In terms of the TREE program, a foul or stinky smell is a sign that a tree is rotting and is unhealthy.


In terms of the TREE program, fungi such as mushrooms or mold, are a sign that a tree is unhealthy. Any fungal bodies will be visible around the trunk or higher in the bark or on leaves.


The growth of a plant from a seed.


A dark layer of wood composed of dead xylem cells and fiber bundles. Over time, the cells harden and becomes stronger, enabling the heartwood to be structural support for the tree.


A process in the water cycle where water that remains on the earth's surface is soaked up by the soil. Trees absorb water from the soil and transport it to the leaves through the stem.

Inner Bark

A layer of bark beneath the outer bark that is composed of cells that transport sap and nutrients throughout the tree. As these cells age, they become outer bark.

Late Wood

The later slow growth of the tree as it progresses towards winter. This later slow growth creates the darkly coloured, more dense wood.


Tree leaf cells are composed of parenchyma cells in long tube-like arrangements. Mesophyll cells make up the middle section of a leaf.

Outer Bark

Composed of dead cells, this is the visible layer of bark and is commonly referred to as cork.


The process of two fluids of different concentrations of a substance, mixing to reach equilibrium.

Parenchyma Cells

These cells provide support and nutrients to phloem and xylem cells and make up the bulk of plant cells.


A layer of tissue that lies just inside the endodermis. The pericycle serves as internal support and protection for the root and it also forms new lateral roots by dividing rapidly in a specific location.

Phloem Cells

A collection of cells responsible for transporting water and nutrients up and down throughout the tree.


The process by which plants convert light energy into chemical energy for food.


The centermost portion of the tree and is composed of soft spongy parenchyma cells. The pith stores and transports water and nutrients throughout the tree.


A process in the water cycle where as more water condenses into water droplets, the clouds continue to grow, until the cloud becomes saturated and too heavy. When this happens, the water droplets fall to the earth as rain, snow, or hail.

Root Sprouting

A way trees reproduce by using a shared root system. In this process, new aspen trees sprout from the roots of a mature aspen tree. Root sprouting produces numerous trees or clones with identical genetic information, leading to a colony of trembling aspen.


A process in the water cycle where the rain or melted snow on the ground flows back into various bodies of water such as rivers, lakes, streams, and oceans. The water will then be evaporated again, starting the cycle all over.


A layer of wood, composed of xylem cells, that is responsible for water transport and storage through the tree's daily water cycle. As the cells mature and die off, the sapwood hardens and becomes more rot resistant, turning into heartwood.


These are trees in areas within a forest that have been measured, mapped, outlined, and described as a distinct group of trees. Stands can be large or small, ranging from a few acres to hundreds. Trees within a stand will share similar characteristics such as age, size, condition, and species.


These are little natural openings in the epidermis that allow for regulated gas exchange between the tree and the atmosphere (stomata is plural).


The process where plants allow water to evaporate from their leaves to pull up water from their roots.

Tree Ring

Visual indicators of the annual and variable growth rate of trees.

Vascular Bundle

This a bundle of xylem and phloem cells that are essentially the veins and arteries of the leaves.

Vascular Cambium Layer

The one cell thick layer responsible for the tree's radial or circular growth.

Vascular Tissue

Large amounts of tissues that help transport nutrients and water throughout the tree.

Xylem Cells

A collection of cells responsible for transporting water up the tree.