Nothia sporangia aspects
deutsche Version

Among the early land plants found in the Rhynie chert, Nothia is distinguished by big tubes, called giant cells in [1], embedded in the epidermis. Since they are no mere giant cells but tubes formed by dissolution of numerous cell walls, as extant euphorbias do to store a poisonous milk there, it had been proposed here that Nothia, too, had formed the tubes as a defense against herbivores. Usually these tubes are not well seen, as in Figs.1,2. Tube cross-sections are clearly seen in the wall of the small sporangium in Fig.3.
The cut face in Fig.2 is suitable as a funny illustration of the attack by some fancy herbivore mistaking the sporangium for a filled feeding bowl.
(See also
Rhynie Chert News 57, Figs.5-7, and discussion.)
Nothia sporangiaNothia sporangium
Nothia sporangium cross-section
Fig.1: 4 Nothia sporangia: with pale wall and dark spores (in the middle), with pale wall and pale spores (in the corner above left), with dark wall and pale spores (above and below right); scattered spores, also in tetrads. Image size 3.5mm, same scale for Figs.1-3.

Fig.2: Nothia sporangium like a feeding bowl with diamonds: black-coated sporangium with clear spores.

Fig.3: Small Nothia sporangium with cross-sections of the typical big tubes in the wall tissue on the left. Image size 1mm.

The scattered spores in Fig.1, partially seen in tetrads, seem to be hollow, with light-brown translucent walls, as they are also known from Horneophyton, for example. The light brown is possibly the natural residue of the decayed organic matter. The conspicuously different whitish aspect of the spores in the other sporangia seen at the edges of Fig.1 might be the result of bleaching by oxidation of the organic compounds left over after decay. Apparently the bleaching has also affected a larger part of the sporangium wall in the middle so that it has become pale yellow.  

By contrast, the sporangium wall in Fig.2 is not bleached but covered with a black coating, probably of microbial origin, while the spores are bright and largely transparent and glittering.
The openings for spore release are not or not clearly seen here. What looks like an indent in the sporangium wall in Fig.2 above left is possibly indicating an opening slot. (See also  Rhynie Chert News 33, 170 .)
  Rh7/24.2, found in 2003: Fig.1;    Rh3/11.3 (0.075kg), found in 1998: Fig.2;   Rh15/58.2 (0.21kg), obtained from Barron in 2011: Fig.3;   (weights refer to the samples before cutting).

 H.-J. Weiss     2021

[1] H. Kerp, H. Hass, V. Mosbrugger: New data on Nothia aphylla,
      in: P.G. Gensel, D. Edwards (eds.): Plants Invade the Land, N.Y. 2001.
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