Description Polytrichum_commune

cross section of leaf showing parallel lamellae (perpendicular leaf surface) @ 125x magnification

the lamellae, ridges of cells run along leaf surface, crenulate (i.e. small rounded teeth) in profile , 5 9 cells high. margins distinctly grooved 2 rows of paired, projecting knobs. marginal cells, when observed in section, may narrow, more typically enlarged , wider beneath. retuse (i.e. rounded apex central shallow notch) notched, , in rare cases divided vertical partition. these cells smooth , brownish in colour , have relatively thick cell walls. sheath cells measure 60 90 µm long 10 13 µm wide. these cells may elongated rectangles or linear structures 20 times long wide. become narrower toward margins. marginal lamina cells 10 15 µm wide , subquadrate (i.e. square).

close-up of capsules (after shedding of calyptra)

the plants sexually dioicous. leaves of perichaetium have long sheath scarious (i.e. membranous) margin, while blades reduced, gradually narrowing finely acuminate tip. these blades have toothed margins, denticulate subentire in outline, roughened smooth, , have costa excurrent. seta, or capsule stalk, 5 9 cm long, , stout , yellowish reddish brown in colour. capsule 3 6 mm long, rectangular cubic in shape, , brown dark reddish brown in colour. sharply 4 winged, inclined horizontal, , glaucous when fresh. peristome measures 250 µm, pale in colour , has 64 teeth. calyptra golden yellow brownish , envelops capsule. spores measure 5 8 µm, may 12 µm.