Leaf Identification

to identify broad and narrow shaped leaves to identify simple and compound leaf groupings to identify leaf arrangement to identify leaf margin characteristics to identify leaf venation to identify leaf structure

Leaf Structure• The Leaf Blade• The blade is the entire leaf unit.

Sometimes this is made up of several smaller leaflets.  

Leaf Veins

Leaf Margin

• The margin is the term used to describe the edge of the leaf.

Leaf Base

• Base is the name given to the part of the blade that is closest to the stem.

Leaf Apex

• The Apex is the tip of the leaf.

Petiole

• The Petiole is the thin stalk that connects the leaf blade to the stem

Stipule

• Stipules are tiny leaf-like structures that may or may not be present at the base of the petiole.

Petiolate and Sessile

• Leaves which have petioles are called Petiolate

• If a leaf has no petiole it is called Sessile.

Seven Main Leaf Structures

Leaf Blade

• The main part of a leaf is the blade.

• Nine major shapes– Linear– Lanceolate– Oblong– Elliptic– Ovate Cordate– Reniform– Spatulate– Orbicular

Linear

• Narrow, with parallel or nearly parallel side 

Lanceolatelance shaped, longer than broad and tapering to a point at the tip

Oblong

• Much longer than wide, with nearly parallel sides

Elliptic

• Shaped like an ellipse, wider at the center and tapering to equal tips

 

Ovulate

•   egg-shaped, broader at the base than the tip 

Cordate

• Heart shaped, either the leaf shape or base  

Reniform

• Kidney shaped

Spatulate

• In the shape of a spatula or spoon 

Orbicular

• Round

Leaf Groupings

• How leaves are grouped on stem– Simple– Compound

Three types of compound

Leaf Margins

• The shape of the edge or margin of a leaf is another way it can be identified. Three kinds of margins are Entire, Toothed, and Lobed.

EntireSmooth no bumps

Toothed

• Shallow bumps

Dentate

• Pointing outward

                                                      

      

Serrate

• Point to the leaf’s tip

                                                      

      

Crenate

• Broad and round

Incised

• deeply cut with sharp, irregular teeth

                                                      

      

Lobed

• deep indents or sinuses

Sinnate

• very wavy margin

Undulate• wavy margin, but not as wavy as a

sinuate margin