The parts of a tree are:
Leaves and Needles
Leaves and needles are the food factories in the tree’s crown. Food-making, or photosynthesis, begins when the sun’s warmth and light is trapped by green chlorophyll in the leaves. This energy is used to combine carbon dioxide from the atmosphere with water drawn from the roots to create sugar and starch. The inner bark then carries this food to all living parts of the tree. In turn, oxygen and water are released into the atmosphere as by-products of photosynthesis.
Every spring the tree grows taller as a new set of branches develops at its top, and wider as buds develop along the older branches, twigs and tips. Soft tissue inside the buds is protected from damage by a tough covering of moisture-saving bud scales.
Cones and Flowers
Trees produce flowers or cones that hold fertilized seeds. In late summer or fall, the seeds come loose and are scattered by wind, water and wildlife. Within each seed is the soft tissue that is the basis a new tree. Seeds have a tough coating that protects them during dispersal to their new home.
Branches and Twigs
Branches and twigs support the leaves, holding them up to receive the sun’s light and warmth. They also produce buds that form new twigs, leaves and flowers.
Trunk or Stem
The trunk is the main stem of the tree. It supports the crown of branches, leaves/needles and transports food and water throughout the tree. The tough, outer bark protects the tree from heat, cold, moisture loss and injury. The soft inner bark carries food from the leaves and needles to all living parts of the tree. Beneath the inner bark is a thin layer called the cambium that each year develops new cells of inner bark on its outer wall and new sapwood cells on its inner wall. The sapwood carries water from the roots up to the leaves/needles. As the tree grows, old inner layers of sapwood die and become heartwood, a rigid fiber that gives the tree its strength.
The roots act as an anchor, holding the tree firmly in place. They grow and spread out underground from the root tips, forming a huge network that draws nutrients to the tree and protects the soil from erosion. Small root hairs grow out from the roots to absorb water and minerals from the soil.