Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 86. (Budapest 1994)

Barbacka, M.: Reconstructions of stomata in Komlopteris Barbacka and Pachypteris Brongniart and their adaptation to climate

The recently examined species of different forms show, among other details, differences in the degree of cutinization on those parts of the guard cells which are found close to the stomatal pit. In some sorts of leaves those parts of the periclinal walls were not preserved, so the cutinization was probably weak. In other sorts of leaves large numbers of stomata possessed well cutinized parts of the guard cell's periclinal walls in the stomatal pit (Fig. 13). This was probably caused by unequal arrangement of guard cells towards the outer surface of the epidermis in different leaves and might depend on the position of the leaf in the plant and on external factors. The guard cells lying underneath the surface of the cuticle (Fig. 7) were probably less cutinised than those lying on the level of the surface, so they were destroyed by maceration or fell out. The exposed guard cells in the stomata of Komlopteris may be related to adaptation of the plant to wet climate. The character of the climate in this area was shown by results of the geological and palynological examinations of the sediments in the Mecsek Mountains. (PAÁLSOLT 1969), where Komlopteris is represented by a great number of leaves. According to them the type of the territory in the Mecsek Mountains was like a delta plain with swamps, marsh vegetation and fen forests (PAÁL-SOLT 1969). Similar conditions were found in Scania in the type locality of Komlopteris [K. nordenskioeldii (NATHORST) BARBACKA, 1994a]. NATHORST (1878) mentioned in his monograph on this flora from Pâlsjo the wet, tropical character of the climate in that territory, and the results of recent examinations confirmed his opinion (PiENKOWSKl 1991). In consequence, Komlopteris may be regarded as a representative of tropical fen. The adaptation to environmental conditions of environment is not so clear in the case of Pachypteris. Based on observations of different species of Pachypteris it is clear that they possess two types of stomata. In one group [P. major (RACIBORSKI) REYMANÓWNA 1963, P. lanceolata BRONGN. sensu DOLUDENKO & SVANIDZE (1969), P. desmomera (SAPORTA) BARALE (1971), P. daincourtii (SAPORTA) BARALE 1984, P. cf. lanceolata BRONGNIART sensu VAN DER BURGH & VAN CITTERT (1984)] the stomata seem to be similar to those of Komlopteris. They were more or less regular, roundish in shape and the outer outlines of the subsidiary cells were protruded. Their similarity to stomata of Komlopteris is visible under a light microscope only, because subsidiary cells seem to form a double ring too. In fact, the lines which divided subsidiary cells into concentrical rings were formed by outlines of guard cells below the subsidiary cells and not, like in the case of Komlopteris, by contact of the cell walls of subsidiary cells. Because of this, their structure is different from bowl-shaped stomata in Komlopteris. The schematic drawing of transversal section of a stoma in Pachypteris daincourtii (SAPORTA) BARALE (BARALE 1984) suggests that the guard cells were probably small in stomata of that type (Fig. 10). The second group of Pachypteris [P. rhomboidalis ETTINGSHAUSEN) NATHORST sensu DoLUDENKO (1971) P. rhomboidalis No BP 60.216.1.(Hung. Nat. Hist. Mus., Budapest), P. banatica (HUMML) DOLUDENKO (BARBACKA 1994b), P. lanceolata BRONGNIART sensu HARRIS (1964) P. papulosa (THOMAS et BOSE) HARRIS 1964], had stomata with irregular and large subsidiary cells (Figs 8-9). Looking from the mesophyll side they reflected the shape of a truncated pyramid with a protruding rim on the top around the stomatal pit (Figs 15-17). It was formed by thickly cutinised parts of guard cell walls. The guard cells, often well preserved, stronger cutinised than those of Komlopteris, were large, with extended poles (Figs 16-17). Their outer margins are often visible under the light microscope below the subsidiary cells and reach beyond the limits of the stomatal pit. The arrangement of guard cells suggests that they were sunken (Fig. 18). Looking from the outer surface, the cuticle was similar to that of Komlopteris, but the holes marking the stomata possesed bend edges (Fig. 18). The proportions of the size of the stomatal pit and the subsidiary cells in Pachypteris differed from that of Komlopteris. While in Komlopteris the width of the stomatal pit ranged between 1/3 and 1/2 of the width of the whole stoma in transversal section, in Pachypteris it was about