Complete Guide of Key Parts of Tree: Names, Functions & Diagram

A tree is a perennial plant with an elongated stem or trunk, usually supporting branches and leaves. It was the old part of the earth before human beings existed. At an early age, most of the earth’s surface was covered by trees. But with time, its percentage decreased. Trees help to increase oxygen in the air, make it clean, reduce pollution, prevent soil erosion and give food to eat. All these needs of human beings fulfill the tree, but how many of you know the parts tree? As a tree fulfills most of our basic needs like food, clothes, paper, furniture, ship parts, and medicines, we should know the parts of a tree. This article helps you to understand the tree parts and their functions. We will see how different parts of a tree form and how they develop.

Also, this article helps us to understand the tree’s anatomy, which includes a crown, trunk, and roots.

Parts of a Tree Diagram

Parts of a Tree, Names, Functions & Diagram

Tree Parts Names


  • Leaf
  • Twig
  • Branch
  • Fruit
  • Foliage

Trunk or Bole

  • Outer Bark
  • Inner Bark
  • Cambium
  • Sapwood
  • Heartwood
  • Pith
  • Growth Ring


  • Lateral Root
  • Tap Root
  • Oblique Root
  • Sinker Roots
  • Fine Roots

Parts Tree & Functions


It is above the part of the trunk, which includes leaves, twigs, branches, limbs, fruits, and foliage. It is a green portion of the tree. 


The primary function of the leaves is to do photosynthesis to grow the tree. During this process, leaves absorb the sunrays falling in them and convert carbon dioxide and water into oxygen, sugar, and carbohydrates. 

It also gives good shade to the tree, keeps the air cool, increases air oxygen percentage, reduces pollution, and more. Nowadays, the leaves of trees are used in Ayurvedic medicines to cure diseases and illnesses. 


Twig develops from the branches, and the leaf grows on them. Water and mineral come from the roots to the limbs and pass to the leaf through twigs. Similarly, food from a leaf passes to different parts of a tree through twigs and branches. 


Thicker limbs develop the branch. The function of the branch is to provide water and minerals to the leaf and food to the other part of the tree.

It also stores the food and uses them in the dormant time when the surrounding temperature decreases, like in winter. It gives structural stability to bear the weight of the leaf, fruits, and twigs. Branches come from the trunk, and on that, the twig grows. 


The limb is the thicker portion that develops from the trunk.


The primary function of the flower is to reproduce. It is colorful and gives an attractive look to the tree. It grows on the twig and also converts into fruit.  


Fruit develops when the flower fertilizes. It contains a seed that helps to grow a new tree. The different tree produces different fruit, which may possess one seed or multiple seeds. 

Trunk or Bole

It is a strong pillar that gives size, form & support to the branches, limbs, twigs and leaves to grow outward and upward. 


The bark is the outer coat of the tree made of dead phloem cells. It helps to protect the tree from heat, water, moisture, worst weather conditions, insects, and different illness.

The outer bark is thick, whereas the inner bark is thin, carrying food from the leaf to the cambium.  


The cambium is a layer that produces partially undifferentiated cells for plant growth, thus, increasing the tree’s thickness. It is from this region that the xylem and phloem grow by division. Each growth season, the tree adds a new cambium layer. It causes the trunk to form yearly rings.


The function of the phloem is to transport sap containing sugar which means it has been converted from leaf photosynthesis to all around the tree and back down to the roots.

The layer that follows the cambium tissue is the phloem.


Sapwood is the third layer of thick-walled cell vascular tissue that transfers sap from the roots to the crown.

The xylem cells present in this region are young and thus pale in color. As xylem cells mature, they become dormant and form the tree heartwood.


It is the densest and heaviest section of the trunk, with the darkest-colored wood. The non-living xylem cells of the heartwood serve primarily to strengthen and maintain the tree. In addition, the heartwood is also vital in tree physiology as a storehouse for sugars, pigments, and oils.


The pith, also known as the medulla, is a tissue found in the stems of vascular plants. It is the core of the trunk and the sapling’s first source of nourishment.

The pith is of parenchyma cells, soft, spongy cells that store and distribute nutrients throughout the plant.

Growth Ring


Roots are hidden and underground parts of a tree that anchor and spread twice the tree crown. Its primary function is to anchor the tree on the ground and give stability in all weather conditions.

It extracts water and mineral from the soil and helps to grow the tree. It stores the reserve foods and prevents erosion of soil. 

As we all know, trees have different types of roots.  

Lateral Root

Lateral roots are the primary roots that sometimes come from the soil surface and extend along the surface. It spreads a long distance along the earth’s surface to collect water and minerals. 

Tap Root

Taproots are the big roots that grow under the surface; other roots grow laterally. 

Oblique Root

Oblique roots grow diagonally and strengthen the tree to stand in all weather conditions.

Sinker Roots

Sinker roots develop from the lateral roots and grow deep in the earth. It takes ups the minerals and water from deep beneath the earth. 

Fine Roots

These are the little roots that develop from the lateral roots. Its function is to boost the root’s absorption capacity. 

Read More-

What are the different parts of a tree?

Trunk or Bole
-Outer Bark
-Inner Bark
-Growth Ring
-Lateral Root
-Tap Root
-Oblique Root
-Sinker Roots
-Fine Roots

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