here is part II of Plagiomnium ellipticum:
d) Seamed leaf border:

e) Polygonal lamina-cells. On a closer look at the chloroplasts you will even find some of them in dividing-process:

f) Stem, cross section in Etzold stain. Central part with central string (hadrom) and surrounding conducting tissue. At the border we see the outer cortex-layer (stereom). This is the way the stem of most leaf-mosses (Bryopsida) looks alike:

Enjoy!