(b) : Vessels are long tubelike structures ideally suited for the conduction of water and solutes. These are made up of a row of cylindrical cells arranged in longitudinal series. The partition walls of these cells are perforated and as such the entire structure becomes tubelike. The region of the wall where perforations occur is known as perforation plate. Vessels are found in the wood of almost all the angiosperms except certain primitive members of the order ranales (vesseless dicots), e.g., Trochodendron, Tetracentron, Drimys, Pseudowintera, etc. Vessels also occur in some pteridophytes, such as Selaginella and in the members of order Gnetales of gymnosperms (e.g., Genetum, Ephedra and Welwitschia).