Leaf Identification	Lesson 3

Leaf Arrangement, Venation, and Margins

After you have determined the shape and grouping of the plant's leaves, you need to examine the arrangement of the leaves on the stem. the structure of the leafs veins, and the leaf margin characteristics.

Leaf Arrangement

Here are the two principle ways leaves are arranged on the stem:

1. Opposite - directly opposite each other on the stem
Examples

2. Alternate - on both sides, but not directly across from one another.
Examples

 Leaf Venation

The lines that appear on the surface of a leaf and look like blood vessels are called Veins

The two main types are:

Palmate

Pinnate

(Yes, these are the same adjectives used to describe compound leaves.)

Leaf Margins

The shape of the edge or margin of a leaf is another way it can be identified. Three kinds of margins are:

1. Entire - smooth, no bumps

2. Toothed - shallow bumps

3. Lobed - deep indents or sinuses

Toothed Margins

A number of margins are named by the kinds of "teeth" they have

Dentate - pointing outward

Serrate - pointing to the leaf's tip

Crenate - broad and round

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Practice

Now test what you've learned about leaf arrangements, venation, and margins (Go to Test Pilot)