Polytrichum, Hedw.

Maier, Eva & Price, Michelle J., 2014, Georg Bojung “ Scato ” Lantzius-Beninga and his contributions on the anatomy of moss capsules: a transliteration from the original German texts, Boissiera 67, pp. 1-79 : 42-43

POLYTRICHUM .

The genus Polytrichum with its relatives in the family of mosses seems to be isolated what concerns the construction of the upper part of the capsule. The presentation, the structure of the peristome teeth, the appearance of a strange membrane, the epiphragm, connecting the teeth and closing the apex of the capsule are phenomena, which, by a superficially observation cannot be related with those known up to now. Before I describe these particularities I will portray the construction of the lower and median parts of the capsule.

As it is known, in the lower part of nearly all species of Polytrichum is a more or less strong thickening which may be taken as an expansion of the seta, the so-called apophysis, see Tab. LXIV. Fig. 31 . ap. It is built by simple parenchyma cells, of interest only in relation to their arrangement or their position;

[original page 586] from the centre, Fig. 31 . ap, they seem to spread to all sides by moving onto both sides of the epidermis, below towards the seta, and above towards the real base of the capsule. In the centre of this base (Tab. LXIV. Fig. 31. b ) a column-like structure rises, c, the columella, which upwards widens to a plate-like disc ( Fig. 31. d ); around the columella is the spore sac formed as a hollow, quadrilaterally plicate cylinder, consistent of four cell layers each and the enclosed mother cells or spores (see the schematic presentation of the transverse section Fig. 31 *. sc). In our presentation (of Polytrichum piliferum ) the spore sac is separated of the columella by a clearly portrayed hollow space ( Fig. 31 . va) and connected to it only by confervoid-like filaments, but below it rises at the capsule base and is connected above with the disc-like widening of the columella. Again by a considerable gap ( Fig. 31 and 31 *. v), filled with confervoid-like filaments, separated from the spore sac, the outermost point of the outer capsule wall (me) can be found, passing above into the annulus and the operculum.

Not in all species of Polytrichum is the structure as described herein for Polytrichum piliferum . Some of them: Polytrichum nanum , Catharinea undulata and so on e.g. deviate in the respect that the spore sac is placed towards the inner side directly at the columella, which means that there is no special gap between the two parts; in all other parts there is no essential difference.

At first, in the upper part of the capsule on the sides of the disc-like widening of the columella a connection to it and the outer capsule membrane or the lower part of the operculum appears, and then the row of the peristome teeth (Tab. LXIV. Fig. 31 , 32. [original page 587] Tab. LXVI. Fig. 33 . Tab. LXV. Fig. 34, 35, 36 . Tab LXVI. Fig. 39 pp and so on) by two or more cell layers separated from the epidermis. The peristome teeth consist of more or less strong bundles of horseshoe-like thick-walled fibre cells, and their upward pointing ends, growing together with the bundles, form a peristome tooth (compare Bruch and Schimper l. l. Polytrichum , describing the construction absolutely correctly) see the longitudinal section Tab. LXIV. Fig. 38 . da, eb, fc, the transverse section Tab. LXVI. Fig. 33 . Tab. LXV. Fig. 34, 35, 36 . Tab. LXVI. Fig. 39 . pp. Between the teeth, when the capsule is not yet deteriorated, appear considerably delicate, also somewhat bent, cells, see Fig. 34, 35, 36 , ip.

Above the disc-like widening of the columella or between this structure and the loose parenchyma of the operculum extend, connecting the points of the peristome teeth, a layer of cells, that are relatively small, horizontally flattened, and their lower membrane is granular and roughly thickened. At the moment of the spore maturation, these cells form, when the operculum detaches, the epiphragm, by destruction of the thickened cell parts arranged immediately above and below it. The disc-like widening of the columella below shrinks and dries out, and the loose parenchyma above detaches with the operculum.*)

[original page 588]

A partly granular thickening, shown by the cells constituting the epiphragm, is found also in the cells that delimit the peristome teeth on the outer and inner sides as well at those cells connecting the base of the peristome teeth with the annulus, see Tab. LXIV. Fig. 32. xp, and finally on some cells appearing between the upper part of the disc-like widening of the columella and the outer capsule membrane immediately below the peristome teeth, Fig. 32. yp.

When the spores are mature the membranes of the above described thickened cells decay into pieces, beginning at the annulus Fig. 32. a, at both sides of the peristome teeth p, and then below and above of the epiphragm ep. The complete upper part of the operculum detaches whilst the columella shrinks and the delicate tissue between the peristome teeth disappears, giving the spores that pour out of the destroyed spore sac a way out of the closed inner space of the capsule.

Figures

Fig. 31. Longitudinal section of a capsule of Polytrichum piliferum, magnification x 15, Fig. 31* Schematic presentation of the central part in transverse section.

Fig. 33.-37. Transverse sections of capsules of the same moss and the same magnifications

Fig. 39. Part of a transverse section of peristome teeth of a capsule of Polytrichum urnigerum, magnification x 500.

Fig. 38. Peristome teeth of Polytrichum commune with its cell base, magnification x 250.