Leaves photosynthesize.  Leaf form has high variability; but it generally is a flattened blade and a petiole, or stalk, anchored at a node.  Many monocots have no petiole; the leaf's base is curved around the stem (e.g., turf).  Some monocots do have petioles though (e.g., palm trees).

Monocot Leaf vs. Dicot Leaf

one	differential category	two
parallel veins with small cross-veins	arrangement of the veins	a multibranched network of major veins with smaller cross-veins
slender and elongated	general shape of the leaf	many, most common include oval, heart-shaped (cordate) and triangular
various	placement of leaves on the stem	various

More on Leaf Placement.

It is called opposite if each node has only 2 leaves in exactly opposite directions (180 degrees).  Leaf placement is called alternate if each node has one leaf and the each adjacent node going up the stem is pointed opposite the previous one.  It is called whorled if a node has more than 2 leaves attached to it.  A simple leaf is one undivided leaf; a compound leaf is what looks like several leafs but because there is no bud base at the bottom of the "leaf," it is a leaflet part of a compound leaf.   Remember this hint:  Look  at the axillary bud!

Examples of Modified Leaves.

1. pea plant tendrils help support itself
2. cactus needles perform very little photosynthesis
3. leaf coloration to attract pollinators
4. ice plant leaves store water

Next:  "Plant Cells."