brief

1. CLASSIFICATION OF LEAVES

2. OBJECTIVES
TO DEFINE AND UNDERSTAND
• Leaf Types: broad, needle-like,
scale-like, evergreen, and
deciduous
• Simple versus compound leaves
• Phyllotaxy
• Venation
• Margin

3. Leaf Types
Leaves are plant organs which are
very important to the photosynthetic
process. A broad leaf usually consists
of the blade (lamina) which is the
flattened photosynthetic portion. This
type of leaf is usually considered to
be deciduous, that is, the leaves drop
during the fall and winter. The petiole
is the stem-like portion of the leaf,
found between the blade and the
branch or stem. Leaves without
petioles are considered to be sessile.
Stipules are leaf-like structures found
near thebase of the petiole
stipule
blade
petiole

4. Simple and Compound leaves
Simple leaves are whole,
undivided leaves growing
from a bud on the stem.
The node is the part of the
stem where leaves are
attached
Compound leaves are
divided into leaflets,
growing from one axillary
bud on the stem.

5. Phyllotaxy
Phyllotaxy refers to the arrangement of leaves on the
stem. There are three basic types of leaf
arrangement:Trees with alternate arrangement have
one leaf at each node. Two leaves at the node, opposite
to each other, demonstrate opposite arrangement.
Three or more leaves on a node are considered to be
whorled.

6. Venation
Venation deals with the arrangement of veins.
Veins are strands of
vascular tissue which
appear prominently on the
blade.

8. Margin
Leaf margin deals with the morphology
or shape of the blade. The margin of a
leaf is another name for the structure of
the leaf's edge.

9. There are many different variations
Entire Crenate
Dentate Serrate
Doubly-Serrate Serrulate
Incised Lobed
Sinuate
Undulate