The key difference between bordered pit and simple pit is that bordered pit has a secondary wall overarching the pit cavity forming a border while simple pit does not have an arching of the secondary wall and narrowing of the pit towards the lumen.
A pit is a thin depressed portion of the secondary cell wall. Pits are used to exchange fluids and communicate with neighbouring cells. Generally, two pits are located opposite to each other as a complementary pair. There are three main parts of a pit. They are pit chamber, pit aperture, and pit membrane. Pits are a characteristic feature of xylem in vascular plants. During the development of a pit, secondary cell wall may over arch the pit cavity, forming a border. Pits with such borders are called bordered pits. Pits without borders are called simple pits.
