Re-interpretation of detail on Aglaophyton gametophyte
deutsche Version

faint lines misinterpreted as newly formed cell wallsThe gametophyte of Aglaophyton (formerly known as Rhynia major) had been discovered in the Lower Devonian Rhynie chert by Remy & Remy and named Lyonophyton rhyniensis [1]. In later papers by Remy & Hass it had been thoroughly described [2,3]. However, a photograph of a detail in [3] strongly suggests an interpretation differing from the one offered there (Fig.1).

Fig.1: Epidermis of Lyonophyton, arrows (supposedly) indicating “secondary divisions” of cells in the vicinity of a stoma, after [3,4].

It is described there as “Epidermis of young gametophyte aerial axis showing secondary divisions of subsidiary cells (arrow heads) that will lead to the formation of rhizoidal bulges”. Conclusions are drawn there from this picture: “Such axes represent adaptations to subaerial and aerial conditions. In the basal portion of slightly older axes, the subsidiary cells of each stomatal complex show secondary serial divisions that develop into rhizoids. This suggests a functional change in the basal parts of the axes from aerial to rhizomatous.”
alleged cell divisions re-drawn to reveal their nature as cracks

The alleged secondary divisions are really shrinkage cracks, which becomes obvious in Fig.2, where the cell walls and the questionable thin lines faintly seen in Fig.1 have been redrawn for better visibility.

Fig. 2: Drawing after Fig.1, revealing the true nature of the faint lines as shrinkage cracks in chalcedony.

Hence, the above conclusions derived from this figure in [3] are not substantiated. The same figure and its misinterpretation have been published once more [4].

H.-J. Weiss    2005,  emended 2014

[1]  W. Remy, R. Remy : Lyonophyton rhyniensis …,
     Argumenta Palaeobotanica (Münster) 6(1980), 37-72, Tafel 7-13.
[2]  W. Remy, H. Hass :  Ergänzende Beobachtungen an Lyonophyton rhyniensis,
     Argumenta Palaeobotanica (Münster) 8(1991), 1-27, Tafel 1-12.
[3]  W. Remy, H. Hass :  New information on gametophytes and sporophytes of Aglaophyton major and inferences ...
    Rev. Palaeobot. Palynol. 90(1996), 175-193.  
[4]  D. Edwards, H. Kerp, H. Hass:  Stomata in early land plants,
    J. Exp. Botany 49(1998) Special Issue, 255-278.
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