부산대학교 도서관

The seta and stem in Leucodon canariensis are examined by means of light microscopy, transmission and scanning electron microscopy. Their anatomies reveal relevant differences although both show a remarkable structural complexity, as their conducting tissues are equally effective in carrying out essential processes. Five types of cells have been recognized in the transverse sections: in both seta and stem: (i) stereids in the external region with a peripheral cuticle; in the stem only: (ii) parenchymatous cells with plasmodesmata underlying the stereids; in the seta only: (iii) an unusual area of nacreous-walled cells without live protoplasm, surrounding (iv) the food-conducting cells (leptoid-like), and again both in seta and stem: (v) hydroids in the internal region. The seta in this species has a peculiar organization and shares some characteristics with polytrichaceous mosses; the ultrastructural similarities and differences and functional significance of these cells are discussed, both systematically and in relation to the habit of the moss itself. [ABSTRACT FROM AUTHOR]