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The Many Parts of a Tree – An Illustrated Guide (Leaves, Trunk and Roots)

Featured image showing many parts of a tree

There are three main parts of a tree: Leaves, trunk and branches, and roots.  Below we set out detailed anatomy illustrations showing all the parts of a tree; illustrations for each section of the tree.

1. Big picture tree anatomy

Illustration showing all the different parts of a tree

Overview parts of a tree explained:

  • Crown: This the top area of the tree an includes branches and foliage (leaves).  This is where photosynthesis occurs (see diagram above).
  • Foliage: the leaves of a tree. It refers to a leaf or the leaves altogether.
  • Taproot: this is a type of root that grows straight down into the ground, with smaller lateral roots branching off from the main taproot. It is called a taproot because it can be thought of as the main “tap” that supplies water and nutrients to the rest of the tree.
  • Lateral root: roots that extend horizontally. These are thinner than the vertical taproots. Lateral roots anchor trees and provide support as well as absorb water and nutrients.

2. Parts of tree leaves

Illustration showing the anatomy of a tree leaf

Parts of a leaf explained:

  • Epidermis layer: it’s like the outer skin of a leaf that regulates the exchange of gases and water for the leaf.  It’s transparent so light can pass through.
  • Cuticle part of a leaf: this covers the epidermis layer which waterproofs the leaf to prevent water loss.
  • Palisade mesophyll: this layer has many chloroplasts that take care of photosynthesis (uses light to convert carbon dioxide and water into glucose for the tree).
  • Spongy mesophyll: As you can see from above, this lawyer is just beneath the palisade mesophyll layer.  Just like the illustration shows, it’s comprised of air spaces and while it has fewer chloroplasts than palisade mesophyll, it also is involved in photosynthesis.
  • Stoma: this is actually a pore on the underside surface of tree (and plant) leaves.  Adjacent “guard” cells regulate the opening and closing of the pore.  This opening allows for gases to exchange between the leaf and air.

3. Parts of tree trunk

Detailed diagram showing the parts (anatomy) of a tree trunk

Parts of a tree trunk explained:

  • Pith: this is the center of a tree trunk.  It’s soft. It’s comprised of living cells. What it does is transports water and nutrients to all parts of the tree.
  • Heartwood: it’s a section made up of dead cells but that doesn’t mean it’s useless.  It helps support the tree and protects it from diseases and pets.
  • Medullary rays: these are thin layers of tissue in tree trunks.  Like the pith, medullary rays transport water and nutrients. 
  • Growth rings: these are concentric circles that signify one year of growth. These rings are formed by the tree adding a new layer of wood between the bark and the trunk each growing season. They are created as a result of patterns in vascular tissues and their growth rate is affected by factors such as rainfall, temperature, and competition.
  • Sapwood:  this is the outer, living layer of a tree trunk that transports water and nutrients from the roots to the leaves. It is usually lighter in color than the heartwood, and is the tree’s pipeline for moving water up to the leaves. The inner cells of the wood lose their vitality as new sapwood layers grow.
  • Cambium cell layer: this layer produces new bark for the trunk each year which protects the tree and helps it conserve water.
  • Inner bark: this is a layer of spongy material that helps transport nutrients created in the leaves to other parts of the tree.
  • Outer bark: this is the “outer” layer (duh) comprised of dead cells. Its primary purpose is to protect the tree.

4. Parts of tree roots

Big picture view of the different parts of tree roots

Close up microscopic view of tree root anatomy

Related: The different parts of flowers and plants

5. The Life of Trees


You’ve seen trees before, but do you know why they are shaped in the way they are? Let’s begin with what is going on under the soil.

Trees are able to stand so tall thanks to their root systems.

Depending on the variety of tree, the roots may grow very deep into the soil to provide the required support for the heavy trunk and branches above, or the roots grow shallow in the soil, but spread out widely.

Root systems are in place not only to provide support, but that is how trees access the water and nutrients from the soil.

Roots suck up water from the soil through osmosis, and then transport it all throughout the body of the tree — all the way up to the leaves in the sky.

The trunk of a tree is made up of woody tissue that provides strength, stability, and flex, as well as vascular tissue that helps transport water and nutrients to all the members of the tree.

Most trees are covered with a layer of bark that helps provide a protective shield for the vulnerable and valuable parts underneath.

As we move upwards, we find ourselves in the canopy or the crown of the tree. This is where branches reach out from the trunk, and sometimes these branches are then divided inter smaller shoots.

Different tree species only have branches at the very top of their trunk, whereas other species have branches that grow out of the entire length of the trunk.

At the end of the branches and shoots are where we find leaves (commonly associated with deciduous trees) or needles (commonly associated with coniferous trees). The leaves are able to capture energy from the sun, and photosynthesize to convert water into sugar (tree food!).


You can think of a forest of trees as capillaries in your lungs. Trees are the reason why humans and animals are able to breathe. They take carbon dioxide out of the air, and turn it into oxygen.

The fewer trees there are on the planet, the more carbon dioxide there will be in the atmosphere. The deforestation of the planet is a major cause in climate change.

Trees also help keep the ground in its place. Deep and ancient root systems prevent the earth from eroding or washing away during severe storms. Trees provide shelter and nutrients for many animals and insects. For humans they provide food, field, shade, construction materials, and much more.

Trees as Individuals

All of this is well and good, but it is also important to view trees as entities of their own, where their primary function is not serve humans. Trees exist in communities. They support each other, they communicate, they learn, they adapt, they thrive, and they perish.

Our survival in inextricable from theirs, but their survival is entirely separate from humans. So in an effort to celebrate the life of trees, we’ve compiled a list of 101 varieties of tree (out of millions).