They occur solitarily, statistically scattered, arranged in turns around the middle axis or grouped together. Such groups can often be found at the cell's ends. It is commonly called scalariform. We will meet this structure again, when talking about vessel elements. The pits are often surrounded by a halo and are then called bordered pit.
Bordered pits are especially common in the tracheids of some gymnosperms.
Their structure can be discerned best in a cross-section through neighbouring cells. The middle lamina between the cells is preserved within the pits. Their centre is made up by a disc of primary cell wall material, called torus . No secondary walls exists in the pit's structure. Bordered pits exist only in cells with secondary walls.