Figure 1.

SEM images of pit membrane in between vessels of different angiosperm species and tracheids of gymnosperm species. (a) The pit membrane from Catalpa bungei C. A. Mey. showing very smooth surface with pit aperture visible through the pit membrane. (b) The pit membrane of Cedrus deodara (Roxb.) G. Don., showing scalloped torus margins and abundant warty layers inside the pit chamber. (c) The pit membrane from the vessel of Salix matsudana var. pseudo-matsudana, showing granular surface with many warty layers. (d) The pit membrane of Cephalotaxus sinensis, demonstrating extremely thick margo. Pm, pit membrane; m, margo; t. torus; wl. warty layer.