Beeinflussung der Blattzellen vonFontinalis antipyretica durch den Bewuchs vonCocconeis placentula

Abstract

In a special habitat near Lunz (Mittersee) long time epiphytism ofCocconeis placentula var.tenuistriata and var.klinoraphis onFontinalis antipyretica leaves causes characteristic, strongly localized alterations in the walls of affected cells. They turn brown, may thicken, and may produce cystolithe-like protuberances into the cell lumina. These reactions obviously are brought about by a specific property ofCocconeis, for other epiphytes do not cause any change. The comparison of theCocconeis vegetation on younger and olderFontinalis leaves shows a considerable variability of the reactions mentioned, and in another habitat none could be found. Apparently several factors cause these reactions. Altogether,Cocconeis placentula is not a completely harmless epiphyte under certain circumstances. The alterations of the moss cells may be interpreted partly as a premature aging process, partly as a defensive action corresponding to alterations induced by some parasitic fungi. Furthermore, the reactions ofCocconeis onFontinalis are remarkably parallel to the influence of the dinococcalean algaRaciborskia inermis onSpirogyra grevilleana.