midrib The central, thick, linear structure that runs along the length of a plant thallus or lamina. It occurs in true leaves as a vein running from the leaf base to the apex and in the leaf-like structures of mosses and seaweeds.

Which vein structure has a defined midrib?

In a pinnately compound leaf, the middle vein is called the midrib. Bipinnately compound (or double compound) leaves are twice divided; the leaflets are arranged along a secondary vein, which is one of several veins branching off the middle vein. Each leaflet is called a “pinnule”.

Which part of a plant has midrib?

leaf structure

…to form the midvein, or midrib. The smaller lateral veins of the leaf are initiated near the leaf tip; subsequent major lateral veins are initiated sequentially toward the base, following the overall pattern of leaf development.