Leaf Morphologies

The leaves of the plants has an important role in the process of Photosynthesis ( converting the Sun's solar energy into food). One factor that makes leaves distinct is according to their petiole (either stalked or unstalked), blade ( compound or simple), edge ( entire/ revolute/ dentate/serrate/ lobed ), shape of the leaf blade (elliptic/ lanceolate/ acicular/ ovate/ cordate/ hastate/ linear), veins (parallel-veined/ pinnate/ palmate) and lastly, to the arrangement of their stems (alternate/ opposite/ whorled/ rosulate).

According to their Petiole:

-petiole is present         -directly from the stem

According to Blade:

Simple- has divisions that does not reach the midbrib of the leaf
Compound- also called as leaflets

According to the Edge:

Elliptical -2 to 3 times longer wide ellipse

Lanceolat- spear-shaped

Acicular- needle-shaped

Ovate- egg-shaped

Cordate- heart-shaped

Hastate- halberd-shaped (wider at the base but lobes ending sharply)

Linear- strip-shaped

According to Veins:

Parallel-veined - the veins run at the same distance to each other.
Pinnate- There is a main nerve, called midrib, from which the other nerves derive, remembering a plume.
Palmate- The nerves diverge from the main point such as the fingers do in the palm of the hand
Network- netlike venation distinguishes it as a dicot.

According to the arrangement of the stem:

Opposite- springing per one node at different levels of the stem
Alternate- two per node, facing opposite sides of the stem
Whorled- several leaves, same level
Basal (rosulate)- ring aroung the stem

So, we have seen the different characteristics of leaves that makes each leaf unique and distinct. However let me ask you, Why do leaves change color in Fall ?<<Click this link

References:
http://www.dkfindout.com/uk/animals-and-nature/plants/leaves/
http://www.botanical-online.com/hojastiposangles.htm#ellíptica1