Spirina U.N.1, Ignatov M.S.2 2008. Branch development and pseudoparaphyllia of Hypnum cupressiforme (Hypnales, Musci) // Arctoa. Vol. 17: 139–160 [in English].
1 Tver State University, Zhelyabova str., 33, Tver 170000 Russia; e-mail: firstname.lastname@example.org
2 Tsitsin Main Botanical Garden of Russian Academy of Sciences, Botanicheskaya 4, Moscow 127276 Russia; e-mail: email@example.com
KEYWORDS: mosses, anatomy, Hypnum, Amblystegium, pseudoparaphyllia, branch development, ontogenesis.
ABSTRACT. 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 m 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.