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LEAF MORPHOLOGY
SIMPLE LEAF
tip - the terminal point of the leaf

blade or lamina - the flattened, green, 
                            expanded portion of a leaf. 

margin - edge of a leaf. 

midrib - the most prominent central vein in a
             leaf. 

lateral veins - secondary veins in a leaf. 

petiole - the leaf stalk (connects blade to
              stem). 

stipules - leaf-like appendages (at the base
               of petiole of some leaves).
 
COMPOUND LEAF
leaflet - secondary leaf of a compound leaf. 

rachis - an extension of the petiole bearing
             leaflets. 

petiolule - the leaflet stalk. 

petiole - the leaf stalk. 

stipules - leaf-like appendages (at the base
                  of  the petiole of some leaves). 
 
LEAF ARRANGEMENTS

alternate - one leaf attached per node, usually
                 staggered (spiral) along stem.

opposite - two leaves (a pair) attached per 
                 node, usually opposite each other. 

whorled - three or more leaves attached per
                node, usually equally spaced around
                the node.