Foliose and
subfilamentose structures around branch primordia are studied in Hypnum
cupressiforme and Amblystegium serpens. In the former species the
branch primordia are surrounded by subfilametnose structures of problematic
homology, while in the latter they are surrounded by the proximal branch leaves
arranged according to the pattern most common in pleurocapous mosses. Series of
cross sections of 2 mm thick were used to study their
early stages of development. Results demonstrate that the branch primordium in Hypnum
has at the earliest stages the same developmental pattern as that in Amblystegium,
but three to five proximal branch leaves soon become split into narrow lobes. Some
lobes may appear at a certain distance from the branch primordium. The
splitting of one proximal branch leaf occurs in Amblystegium only
occasionally. The principal difference between the proximal and more distal
branch leaves seems to be absent, thus the segregation of pseudoparaphyllia as a
separate morphological structure seems unnecessary, despite the former may have
contrastingly different shape.