Fig.
7.3-2.
Transverse section of wood of Menispermum (a vine called moonseed that is
occasionally cultivated). This transverse section has caught a simple
perforation plate that lies parallel to the plane of sectioning. The rim of the
plate is indicated between the two arrows, and the
perforation is the entire circular white area. The rim so narrow that
a first impression is that this is just an ordinary vessel element or maybe one
with a slightly thicker wall: it would be easy to accidentally think that the
perforation is the entire lumen of the element.