Examples from the Web for midrib
The leaves are simple, and except for the midrib are only one layer of cells thick.
They have straight primary veins running from the midrib to the points of the teeth.American Forest Trees|Henry H. Gibson
The midrib is a little paler than the rest of the frond, and is rather prominent on the under surface.Beautiful Ferns|Daniel Cady Eaton
Another species—D. hypoglossum—is characterised by the leaflets of the midrib bearing still smaller leaflets in the same manner.The Sea Shore|William S. Furneaux
Fruit-dots oblong in chain-like rows along the midrib both of the pinnæ and the lobes, confluent when ripe.The Fern Lover's Companion|George Henry Tilton