The
midvein or primary vein is the main or central vein of a leaf from which arise
the secondary or lateral veins.
More
frequently called midrib or
stem of the leaf, especially when it is prominently raised or
depressed, the midvein is the main or central vein of a leaf from which arise
the secondary or lateral veins. It is usually continuous with the petiole and is often
raised above the lamina (the leaf
blade). On a compound leaf, the
midrib (rachis) extends from the
first set of leaflets (where the
petiole ends) to the end of the leaf.
