Pinnate or Palmate: Sorting Out Dicot Leaves
 

	Fun Experiment to Try at Home!
		Purpose To identify palmate and pinnate leaves.   Materials - wooded area (school yard or park) - diagram sheet of types of leaf vein patterns (these can be found on page 62 of Janice VanCleave's Science Through the Year, as well as in biology textbooks and tree and plant field guides) - binoculars   Procedure 1.  Take a walk through your schoolyard or another wooded area. Using the diagrams of leaf vein patterns, find as many different leaf types as possible. 2. Binoculars may be used to observe distant plants. 3. Record the number of each type of leaf found in a data table. 4. You may wish to use field guides to identify the plants.   Sum It Up! The shape of its leaves is one way to tell one plant from another.

Do some leaves have fingers?
 
The blade of a leaf is strengthened by the many veins that run through it. Some of the veins are larger than others. The arrangement of these large veins forms one of two patterns: parallel or netted. In leaves with the parallel pattern, such as those of a lily or grass, the large veins are parallel, or nearly so, with one another. In leaves with a netted vein pattern, such as those of a sunflower or an oak tree, the veins branch.

Netted patterns can be grouped into palmate and pinnate. If the large veins in the netted pattern all start at the end of the petiole, the stem-like portion of the leaf that supports the blade, and extend through the blade-like fingers from the palm of a hand, the vein pattern is called palmate. The leaves of the sugar maple tree are palmate. Leaflets that radiate from a common point at the end of the petiole, such as those of clover, the horse chestnut tree, poison ivy, and Virginia creeper, are called palmate leaflets.

If a single large vein runs through the center of the leaf and smaller veins branch from it in a feather shape, the pattern is call pinnate. The leaves of an oak are pinnate.

Leaflets that are attached along a central stalk, such as those of the rose, ash, walnut, and hickory, are called pinnate leaflets.

For more information about leaves, see "Janice VanCleave's Science Around
the Year." (New York: Wiley, 2000)