1. Dendrology: Tree Parts and Functions
Forestry

2. A Tree Is…
A tree is a woody plant that has a well-defined stem and a formed crown usually at least 8 feet tall.
The three main parts of a tree are:
roots
trunk (a.k.a. stem or bole)
crown

3. Roots
The purpose of roots is to anchor the tree and absorb water and nutrients.
Rootlets are the small branches that form off the main root.
Root hairs are fine, hair-like roots that absorb water and nutrients from the soil.
Pine trees lack root hairs so they have mycorrhizae fungi to serve that function.

4. Roots
A tap root is a large main root that grows straight into the ground.
Lateral roots are roots that grow horizontally from the tree.
Trees with shallow root systems or that are in heavily cut-over areas are at risk for windfall.

5. The Trunk
The purpose of the trunk is to conduct water and nutrients from the roots to the crown.
Heartwood is the older dark-colored, center portion of the tree trunk.
The wood at the core of the tree is dead so its purpose is only to provide strength to the tree.

6. The Trunk
Sapwood is the light portion of a tree cross-section and it is living.
The living portion carries nutrients and also serves as storage for food synthesized in the leaves.

7. Four Parts of the Trunk Heartwood – purpose is strength
Xylem – nutrient flow upward
Cambium – tree growth
Phleom – carries food downward

8. The Bark
The outer bark is a dead, nonfunctioning layer that’s purpose is to protect the living tissue.
It is formed by a thin layer of cells called the cork cambium.

9. The Crown
The part of the crown that grows in height is the terminal bud.
The purpose of the crown is to serve as the manufacturing part of the tree.

10. Photosynthesis
is the process of converting carbon dioxide and water into food for the tree using the energy of the sun
Most of the water carried to the crown enters the atmosphere as vapor through a process known as transpiration.
Water exits the tree through leaf pores called stomata.
Respiration is the process of a tree consuming oxygen.

11. Tree Growth
The age of the tree can be determined by examining the trunk cross-section and counting the annual rings because each year produces one growth ring.
Summerwood is the dark-colored area of a tree’s growth ring.
Springwood is the light-colored area of the ring.

12. Tree Growth
Trees that are closely-spaced or subjected to drought or stress will grow slower and produce rings that are narrow.
Trees that are well-spaced and have abundant rainfall will grow faster and produce rings that are wider.

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