What Is a Compound Leaf? Pinnate and Palmate Leaves Explained

The short answer

A compound leaf is one leaf split into separate leaflets on a shared stalk. Pinnate compound leaves have leaflets lined up along a central axis like a feather, as on ash and walnut. Palmate compound leaves have leaflets spreading from one point like fingers, as on buckeye. A bud sits only at the base of a whole leaf.

That bud rule is the key to telling a compound leaf from a twig full of small simple leaves.

What is a compound leaf?

Leaves come in two basic forms. A simple leaf has one blade, even if it’s deeply lobed like an oak or maple leaf. A compound leaf has its blade divided into two or more separate leaflets.

The NC State Extension Gardener Handbook chapter on botany explains that the stalk of a compound leaf is the petiole, and the central axis that carries the leaflets is the rachis. Each leaflet may have its own tiny stalk, called a petiolule.

Sources: NC State Extension, Colorado State University Extension.

How do you tell a compound leaf from a simple one?

Look for the bud. A bud forms in the angle where a whole leaf meets the stem. There’s no bud where a leaflet meets the rachis.

The Colorado State University Extension botany notes (CMG GardenNotes 120) use this check to sort leaves. Follow the leaflets back until you find a bud. Everything beyond that bud is one leaf.

Another clue is that all leaflets on a compound leaf lie in one flat plane, while simple leaves on a twig often point in different directions. In fall, a compound leaf may drop as a unit, or the leaflets may fall first and the rachis later.

Our post on cannabis leaf anatomy explains the leaf parts named here.

What is the difference between pinnate and palmate?

Pinnate means feather like. Leaflets line up in pairs along both sides of the rachis. Odd pinnate leaves end in a single leaflet at the tip. Even pinnate leaves end in a pair. Bipinnate leaves divide twice, so each side branch carries its own row of leaflets, giving a lacy look.

Palmate means hand like. All leaflets attach at the tip of the petiole and spread outward like fingers. Buckeyes often have five to seven leaflets.

The NC State Extension Gardener Handbook glossary defines these and related terms, such as trifoliate, for leaves with three leaflets, like clover.

Why does it matter?

Leaf type is a big clue in plant ID, and with arrangement it narrows choices fast. For example, an opposite, pinnate compound leaf on a tree points toward ash. An alternate, pinnate leaf with many leaflets points toward walnut or hickory.

Cannabis is a familiar palmate example. Its fan leaves carry several narrow leaflets from one point. Our post on cannabis seedling true leaves shows how the leaflet count grows as the plant matures. Our post on what cannabis leaves can tell you covers what leaf color and shape can say about plant condition.

How to: step by step

1. Pick a leaf and follow it back toward the stem.
2. Find the bud at its base.
3. Count blades beyond the bud.
4. One blade means simple. Several leaflets mean compound.
5. Check if leaflets run along an axis or spread from one point.
6. Note leaf arrangement on the stem as well.

Troubleshooting

Unsure if it’s a leaf or a twig. Look for the bud. Leaflets have none.

Leaflets fall separately in autumn. Normal on many compound leaves.

Deep lobes look like leaflets. If the blade connects, it’s a lobed simple leaf.

Count of leaflets varies. Normal. Look at several leaves.

Three leaflets indicate a trifoliate compound leaf.

Recognizing a compound leaf makes many trees and shrubs easier to name. Kind Seed Co shares more plant tips in outdoor growing.

Sources

• Extension Gardener Handbook chapter 3: botany, NC State Extension, Extension Gardener Handbook chapter 3
• Botany (CMG GardenNotes 120), Colorado State University Extension, Botany (CMG GardenNotes 120)
• Extension Gardener Handbook glossary, NC State Extension, Extension Gardener Handbook glossary