Venation

The way veins are arranged on a plant leaf can tell you a lot about that plant. That pattern of arrangement is called venation or veination.

There are complex classification systems for leaf venation, but all you really need to know is that there are four basic patterns: pinnate, palmate, parallel, or dichotomous. 

Orange leaf (Kate Russell)

Pinnate

Pinnate venation looks like a feather, with the primary vein emerging from the center of the base of the leaf and smaller veins, called veinlets,  occurring at intervals and pointed outward at an angle. Pinnate venation is seen on citrus, walnut, and pistachio.

Sunflower leaf

Grape leaf

Palmate

Palmate venation looks more like a hand with three or more veins radiating from the base. Grape, pumpkin, rhubarb, and sunflower are all examples of the palmate venation seen in most dicots and eudicots.

Millet leaves (Kate Russell)

Parallel

Two or more equal veins start and end together at the leaf ends while running parallel to each other through the middle. Parallel venation is common to monocots, such as millet and other grasses.

Ginkgo biloba leaves (Jakub Fryš, CC BY-SA 4.0)

Dichotomous 

Dichotomous venation is seen as repeated forking or Y-branching, as seen in Ginkgo biloba leaves.

Other venation patterns

You may also run into a few other leaf vein arrangements that don’t conveniently fall into one of those four groups. For example:

• If two or more secondary veins arch halfway to nearly all the way to the tip, it is called acrodromous.
• If the primary vein splits into more primary veins, it is called palinactodromous.

When you are trying to identify an unknown plant, venation can help solve the mystery!