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Globular Mosses
Flora (1986) 178: 73-83 VEB Gustav Fischer Verlag Jena
Globular Mosses ERWIN BECK, KARL MAGDEFRAU and MARGOT SENSER
Abstract On bare soils, subjected to subarctic climate conditions, lenticular to spherical moss balls have been observed which were completely unattached to the substratum, This article summarized the present knowledge on this unique life-form of foliar mosses, starting with a short treatise on the history of discovery. Then the geographical distribution of globular mosses on the subantarctic islands, the subarctic regions and in the temperate zone is reported. Abundantly, moss balls occur in the alpine zone of high mountains in tropical Africa, especially on Mt. Kenya. A taxonomic approach (Table 1) revealed that globular mosses are representatives of acrocarpous genera which usually form dense hemispherical cushions. As shown by the material from Mt. Kenya [Grimmia ovalis (HEDW.) LINDB.] the globoid shape originates by continual motion either of fragments of moss cushions which have been ruptured by frost or of single moss plants or small aggregations thereof which form a loose carpet on otherwise bare soil. Wind and solifluction which is due to nocturnal needle-ice formation and thawing of the soil in the day time could be demonstrated by two field experiments as moving forces. Structural analysis of the 0.5 to 8 cm large balls of Grimmia ovalis showed three zones: The outer layer of living parts is followed by a zone of morphologically intact but dead sections of the plants while the core consists of a peaty material composed of disintegrated leaflets, rhizoids and stems and of minute soil particles as well. The velocities of uptake of water and of methylene blue (as a model substance for cationic nutrients) into a spheroid of Grimmia ovalis has been determined under field conditions.
1. Introduction A special feature of plant life on bare soils of subarctic and high alpine regions which are subjected to vigorous frost heaving and solifluction is the occurrence of thalli of algae and lichens and of cushions of mosses which are not attached to the substrate. Under certain circumstances the latter can develop a lenticular or even completely spherical shape (Fig. 1) and thus have been referred to as globular or spherical mosses or moss balls. Taxonomical work on this specialized life-form has revealed that the capability of developing unattached globes is not confined to a single species or family but was aquired by a variety of mosses which in other habitats form attached cushions.
2. Discovery of globular mosses On the occasion of the transit of Venus in December 1874 the U.S. sent an observation expedition to Kerguelen Island. The Surgeon, J. H. KIDDER, availed himself of collecting plants especially at the southern part of the island. Among 28 species of mosses, which were identified by Th. P. JAMES, were two new species of Grimmia. One of these, G. kiilderi, was described as "compacte globosa pulvinata" (JAMES 1875, 1876) and an ecological observation on this species was added: "The small balls formed by this curious moss seem not to be rooted to another plant, but to be blown about by the wind indiscriminately ... Very local". When in 1898 the German deep sea research expedition "Valdivia" disembarked at Kerguelen Island, the botanist A. F. W. SCHIMPER, too, observed the globular mosses, and without knowledge of 6
Flora, Bd. 178
E. BECK et al. Tab)P 1. Compilation, taxonomieal affiliation and provenance of foliar mosses which have been reported to form globoids. An asterisk indicates an illustration in the reference Family jSpccies
Locality
Reference
Kerguelen Island Prince Edward Island Marion Island
SCHENCK 1905* HUNTLEY 1971* H. HERTEL, Botan. Staatssamml. Mu· nich Nr. 24126a
Norway Alaska
LID 1938* BENNINGHOFF 1955
Kerguelen Island Alaska Prince Edward Island
SCHENOK 1905* BENNINGHOFF 1955 HUNTLEY 1971*
Jan Mayen Marion Island Jan Mayen
LID 1938 HUNTLEY 1971 * LID 1938*
Mt. Ontake, Japan Norway Kerguelen Island
TAKAKI 1956, 1958 LID 1938* JAMES 1875
Mt. Elgon, Kenya
HEDBERG 1964*
Mt. Kenya, Kenya Mt. Kilimanjaro, Tanzania
HEDBERG 1964* POTIER DE LA V ARDE 1955 leg. E. BECK 1979, det. M. BrZOT
Andreaeaceae
Andreaea parallela C. MB"ELL. - regularis C. ::\1B"ELL.
-
rupestris HEDW. (= A. petrophila EHRH.)
Ditrichaceae
Ditrichum conicum (MONT.) MITT. (= Blindia aschistodontoides C. i\IuELL.) - flexicaule (SCHWAEGR.) HAM - strictum (H. HOOK et WILS.) HAM Dicranaceae
Dicranoweisia crispula (HEDw.) MILDE Holodontium pumilum (MITT.) BROTH. Kiaeriafalcata (HEDw.) HAGEN Grimmiaceae
Grimmia decalvata CARD. - donniana SM. - kidderi JAMES - laevigata BRID. (= G. campestris BUROHELL) ovalis (HEDw.) LINDB. (= G. commutata HUEB., G. ovata WEB. et MOHR)
Mt. Kenya, Teleki Valley
Rhacomitriumfasciculare (HEDw.) BRID.
Breidamerkurjokull, Island
- sudeticum (FUNCK) B.S.G. Schistidium apocarpum (HEDW.) B.S.G.
Norway Amchitka Island, (Aleutian Islands)
EYTHORSSON 1951, cf. SHAOKLETTE 1966 LID 1938* SHACKLETTE 1966*
the former publication by JAMES, described them on the basis of photographs (SCHENCK 1905) as follows (translated): "The most marvellous forms of mosses in the Azorella formation are represented by the species designated as globular mosses, their diameter varying between that of a cherry and a middle-sized potato. The smaller balls are formed by Blindia aschistodontoides, the larger ones, however, by Andreaea parallela, the stems of which regularly radiate from a central core of soil or a pebble. Strong winds roll these bodies over large distances; similar to other wind-blown structures they concentrate at certain places until a gust of wind again blows them away. Thus, successively the different faces are exposed and are able to develop."
Globular Mosses
75
3. Distribution of globular mosses 3.1. Subantarctic regions Even at the place of detection, on Kerguelen Island, globular mosses occur only on special sites what was commented by JAMES by the term "very local". Therefore it is not surprising that this life-form was not included in the comprehensive records of mosses of that island established by the British "Venus Expedition" (MITTEN 1879), the German "Gazelle-Expedition 1874~76" (MULLER 1883, 1889) and on the occasion of the "International Polar Research 1882~83" (MULLER 1890). E. WERTH, an excellent observer who studied the vegetation of Kerguelen Island for 15 months during the "Deutsche Sudpolar Expedition 180l~3" wrote: "Globular mosses as collected and described by SCHIMPER could never be observed by us (1906)". According to HUNTLEY (1971) moss balls occur on other subantarctic islands, too, namely on Marion and Prince Edwards Island: "Several moss species besides occuring as small cushions and buttons, develop a spherical shape in certain localities. Balls of one to ten centimetres diameter of Holodontium pumilum, Andreaea spp. and Ditrichum strictum were especially abundant on fieldmark on Prince Edward Island ... The frequency of fluctuations across freezing point on the Marion and Prince Edward Island may be sufficient to produce moss balls". H. HERTEL (Munich), in 1982, collected globes of Anareaea regularis (Botanische Staatssammlung, Munchen Nr. 24126a) at the N-coast of Marion Island and commented: "Only a small percentage of the moss balls was found to be completely unattached; the majority are attached to the substratum forming 3/4 to 5/6 spheres". Similarly, Ditrichum strictum (det. R. OCHYRA) was found by him as globoid. From the bryologically well investigated South Georgia, spherical mosses have not yet been reported, although those species which produce this life-form on Kerguelen, Prince Edward and Marion Islands, are present. 3.2. Subarctic regions From subarctic areas subjected to similar climatic conditions as the subantarctic, globular mosses have been reported, too. LID (1938) observed so-called "mossbollar" of Kiaeriafalcata and Dicranoweisia crispula on Jan Mayen (between Iceland and Spitzbergen) and of Rhacomitrium suaeticum, Andreaea rupestris and Grimmia aoniana in the alpine regions of Norway. SHACKLETTE (1966) found "unattached moss polsters" of Schistiaium apocarpum at Amchitka Island (Aleutian Islands). The socalled "J6klamys" (glacier mice) occuring on Iceland (EYTHORSSON 1951) and in the area of the Matanuska-glacier (Central Alaska; BENNINGHOFF 1955), representing pebbles which are completely covered by mosses (Anareaea rupestris, Ditrichum flexicaule) may also be grouped into this category. 3.3. High mountains of the temperate zone Up to the present, globular mosses have only been found in one place of the Eurasian Mountains, namely on Mt. Ontake in Central Japan (TAKAKI 1956, 1958). Close to the top (at an altitude of 3,100 m) Grimmia aecalvata produces spheroids of 0.5 to 1.0 em in diameter. 3.4. Afroalpine regions OLOV HEDBERG (1964), the investigator of the alpine vegetation of the East African high mountains, when participating in the "Swedish East African Expedition 1948" detected globular mosses on solifluction soils at the Western slopes of Mt. Kenya at an altitude of 4,200 m and on Mt. Elgon at 4,300 m. POTIER DE LA V ARDE (1955) identified these specimens as Grimmia campestris and G.ovata, respectively.
o·
7G
E.
BECK
et al.
He cOlllmented on the latter "Les touffes presentent sous la forme de balles spheriques, n'avant aucune adherence avec Ie substratum". Two of the authors of this article, in 1979 and 1980 were able to collect a bulk of material at Mt. Kenya (Teleki Valley 4,000-4,500 m altitude) which provided the basis for the structural studies described in chapter 6. Globular mosses (Grimmia ovata) have also been recorded from the East side of Mt. Kilimanjaro (HEDBEBG 19(4); they occur on the western slopes of Kibo, too, at an altitude of 4,600 to 4,800 m. From the Andes, the occurrence of moss balls has not yet been reported. However, according to similarity of climatic and edaphic conditions, this life form could very well exist at altitudes above 4,000 m.
4. Taxonomic affiliation of globular mosses Globular mosses consistently belong to acrocarpous families of leafy mosses; they are representatives of genera which usually form dense hemispheric cushions (MAGDEFRAU 1982). Table 1 provides a survey of the species recorded up to the present as to form balls or globoids.
5. Origin of the globoid shape In the Afroalpine region of Mt. Kilimanjaro (Tanzania), Mt. Elgon and especially of Mt. Kenya (both Kenya) globular mosses are found regularly in areas which are subjected to considerable soil movement due to needle ice formation and solifluctien. These phenomena were usually observed on horizontally layered or gently slopir:g bare soils which contain sufficient water to enable ice crystals to be formed duril~g the nocturnal frost period. According to the literature the formation of a moss globoid commences with the fragn:entation of a moss cushion and detachment of small portions or even single plants thereof from the substrate. Heavy winds (AUBERT DE LA RUE 1968; SHACKJ,ETTE 1966; JAMES 1875), frost rupture (HEDBERG 19(4) or kicking by animals e.g. the caribou (STEERE, personal communication 1979) have been considered to be responsible for the disintegration of an attached moss cushion. In the Afroalpine regions disruption of moss cushions by frost is regularly found and quite obvious especially on rocky substrates (Fig. 2). The fragments are often observed downhill of moss-covered rocks; they are turned around by soil movement resulting in an allround growth, whereby the globoid shape gradually develops. However, because of the original hemispherical cushion profile, those moss balls never become ideal spheres but consistently show two or more differently developed portior:s (Fig. 3). This type represents the moss balls found predominantly on sloping solifluction soils. On the contrary, spherical moss balls are regularly observed in great numbers on horizontal soils exhibiting various types of the so-called solifluction polygons. On such localities moss cushions were found predominantly inside and at the edge of Festuca tussocks. Single stems rather than larger fragments become separated from the cushicns probably due to frost rupture combined with the grating motion of the grass blades. As a consequence, single moss plants or small aggregations thereof were found to form a loose carpet from which spherical moss balls develop by branching ard continual motion (Fig. 4). Due to increasing immobility the large balls apparently rest for longer periods on the same side and thus flatten with time. Two environmental factors are responsible for the motion of the moss balls, namely solifluction and wind. In an experiment performed at Teleki Valley (Mt. Kenya) at an altitude of 4,200 m the effect of both factors was studied. Moss balls were labelled
77
Globular Mosses
Fig.!. Moss balls of Grimmia ovalis on gently sloping soil at Teleki Valley (l\It. Kenya) at an altitude of 4,300 m. (Foto E. BECK, March 1983). Fig. 2. Disruption by frost of cushions of Grimmia ovalis growing on rock peak, 4,600 m altitude; Foto E. BECK, March 1980).
PIt.
Kenya, Hiilnel
Fig. 3. Moss ball which has originated from a fragment of a cushion and thus shows differently developed faces (Mt. Kenya, Castle Rock, 4,500 m, Foto K. LIEDL, March 1980).
, 78
E.
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BECK
et al.
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79
Globular Mosses
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110 -410.1980 4.10. -1110.1980
E
~ ___ ------------------------_____-8 8
Fig. 5. Dislocation and movement of globular mosses by solifluction and wind on a horizontal area. Size and shape of the moss-balls are true to scale. The spheroids were labelled at the beginning of the experiment by a thread drawn diametrically through the core. 19.2.85 -13.1985 -631985 80 cm ---....------;-,
N
,-...----><----
x
x
E
W .:;
x
E
x
co
900
Cft Festuca pilgeri tussock
Fig. 6. Movement of globular mosses by solifluction alone on a horizontal area protected from wind. Other conditions as in legend of Fig. 5.
Fig. 4. Collection of moss balls from a horizontal area of bare soil showing the development of the spherical shape from single stems (Mt. Kenya, Teleki Valley, 4,200 m; Foto K. LIEDL, March 1980).
80
E.
BECK
et al.
in their natural habitat with a thread, one end of which was marked and the location of the globes was sketched into a diagram. After periods of 4 and 11 d, respectively, the situation and orientation of the mosses was analyzed. The results are shown in Fig. 5. Only one out of fourteen balls was found unchanged. All others had been turned and (or) removed from their original position. The data do not show a correlation between the size of the ball and the extent of movement. In this experiment both factors, wind and solifluction have affected the situation of the mosses. In another experiment the effect of wind was excluded by protection of a similar area by a stonewall. The experiment was started in the dry season. Due to dryness of the soil solifluction was not observed and consequently the mosses kept their position. Subsequently the area was then watered daily. Considerable solifluction resulting in the formation of gravel polygons occurred after a few nocturnal frosts and the moss balls started toturn around (Fig. 6) but remained close to their original position on the field. Expectedly the smaller balls appeared to turn somewhat faster than the larger ones. From these experiments it is obvious that wind is responsible for the dislocation of the moss balls while solifluction alone would only turn the globoids around. Although there is wind all year in the Afroalpine zone, its effect is mainly observed during the dry season when the moss balls are dry, since the weight of the wet balls would be too heavy for movement by an air stream. On the other hand growth of the mosses requires humidity and thus preferentially takes places under conditions where also needle-ice formation and solifluction occur.
6. Structure of globular moss balls The diameter of the moss spheres of Grimmia ovalis varies between 0.5 and 5.5 cm; larger specimens (6 to 8 cm), however, independently of their mode of origin are of discoid shape exhibiting two flanks of preferential reclining while the margins represent the main areas of growth. JAMES (1875, 1876) reported the globes of Grimmia kidderi to be "found only in a barren state": Similarly, the spheres of Grimmia oval is do not develop sporophytes, although the attached cushions of this speces, even those found on rocks amongst the balls, are copiously fertile. Obviously the rolling motion of the globes impedes thriving of the spore cases. The latter, however, have been observed on large discoids. Apparently these balls, due to their relative immobility rest sufficiently long on one flank to enable development of sporophytes at the margins. Independently of the mode of origin, the stems in a moss ball of Grimmia ovalis show radial growth from a central core of soil-like material. As is evidenced by the ample material of Grimmia oval is from Mt. Kenya (110 specimens) the structure of the globular cushions is similar to that of the hemispherical, attached tufts. Both types, by basitonic as well as acrotonic innovation stems likewise extend in length and width (Fig. 7). Heterophylly is pronounced in the globular form of Grimmia ovalis to a similar extent as in attached cushions. It is remarkable that the density of the rhizoids increases towards the center of the spheroid. The outer layer which is formed by the green parts of the plants usually does ot exceed a thickness of 6 mm. Towards the center it is followed by a brownish layer of dead, however still morphologically intact sections. The innermost portion of the spheroid, the soil-like material, consists of fragments of leaflets, stems and especially rhizoids and thus resembles a moss peat. In particular the plant sections of the second, brownish layer show a cover of mineral dust and consequently minute mineral grains are also detectable in the peaty material of the core. Obviously, soil dust is continuously blown into the globoid and then adheres to the plant surface and thus might contribute to the mineral nutrition of the moss.
1
81
Globular Mosses
B Fig. 7. Grimmia oval is (HEDW.) LINDB. A. Acrotonic and basitonic branching of a stem isolated from a spherical moss ball of 2.5 cm dia· meter. B. Stem with sporogon and calyptra from the edge of a large discoid moss ball (Fig. 4, lower row, at the right).
Sometimes moss balls contain a larger portion of sand or even a small stone in their center. Apparently such globoids originate from a larger fragment of an attached cushion which upon disintegration kept contact to a loose piece of substratum. In the temperate regions an analogous formation of a moss ball may occur but rather casually and only from a species producing dense tufts (MAGDEFRAU 1982). If by exogenous forces parts of tufts or young portions thereof were teared away and turned upside down, innovation stems can develop on the original lower side. Movement of such tuft fragments by wind could then result in the formation of discoidal, ellipsoidal and even spherical moss balls. "Spheroidal balls" of Leucobryum glaucum, "entirely unattached" were described in DIXON's handbook (1924) and have been observed recently by Prof. Dr. W. PROBST near Flensburg (F.R.G.) in a forest which is exposed to heavy winds (peronal communication 1982). Under certain circumstances, pleurocarpous mosses, too, are able to survive for a while after having been separated from their substratum, as has been reported by DIXON (1924) for Thamnium alopecurum (Great Britain) and by MARTIN (1952) for Echinoaium hispiaum (New Zealand). However, such unattached mosses are not comparable to the globular life form described in this article. Unlike Grimmia, unattached specimens of both species differ in habit, size, mode of branching and number of branches from the normal form (MARTIN 1952) and are found rather as discoids than as globoids. Similarly, the so-called moss balls of Jungermannia pallida (HORIKOWA 1960) and of Leptodictyum riparium (OeHI 1956) which have been observed in lakes and creeks of Japan (OSADA 1956, IWATSUKI et al. 1983) do not represent globular mosses in the true sense: They are comparable to the "sea balls" which are well known to originate from algae or even dead plant material (e.g. Posiaonia fibres) by the rolling forces of the waves.
II. II
E.
BECK
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et a1.
A Fig. SA. Cross section of a moss-ball which has been sitting for three days on methylen blue powder (xx) in its natural habitat. Stained areas are indicated by thick lines and dots. Those parts which were still green (lines) and brown (dots), respectively , are drawn by thin symbols. Revolution of the spheroid during the period is shown by the circular arrow. Fig. SB. Drawing of a single moss plant removed from the indicated area of the moss ball shown in A. Thick lines and dots show the stained parts.
7. Uptake of nutrients and water Direct uptake of water and dissolved nutrients by those leaflets which are in direct contact with the soil appears to be very probable. The results of the followinge xperiment confirm this assumption : A moss spheroid was put into moist soil to which a few grains of methylen blue had been added and the distributio n of the dye in the ball was analyzed after 3 d (Fig. SA). During that period the moss ball had turned about 90° and two thirds of the spheroid were stained. All those plants which had been in contact with the dye were completely blue. One of the stems which had not directly been in contact with the dye was investigate d microscopi cally. Only two of the green leaflets (probably growing leaflets) showed blue tips (Fig. SB). However, the stem, the whole felt of the rhizoids, the older brownish leaflets and two shootlets were completely stained. Thus it appears that the dissolved dye has been taken up into the central core from which it entered the dead parts of the plants by capillary forces. From there it had been transporte d to the growing regions of the stem. Methylene blue at the existing pH-value represents a monovalen t cation and thus should strongly be adsorbed by the cell wall material of the moss which is thought to be negatively charged. This ionic interaction might be responsible for the relatively slow spreading of the dye over the moss ball as compared to water. Even if only one edge of the globoid was watered, the whole ball was found to be wet after a few minutes.
Acknowledgement The field work waS conducted during several expeditions devoted to the project "Ecological Research on AfroaJpine Flowering plants" supported by the Deuteche Forschungsg emeinschaft .
Globular Mosses
83
The authors wish to thank the Kenyan authorities for the permlsslOn to conduct research at Mt. Kenya National Park. They are grateful to Dr. R. SCHEIBE, University of Bayreuth, for assistance with some of the field experiments.
References AUBERT DE LA RUE, E. (1968): Balles des mousses vagabondes, curiosites vegetilJes des iles Kerguelen. Terres australes et antarctiques francaises 45: 3-9. Paris. BENNINGHOFF,1\1. S. (1955): Joklamys. Journal of Glaziology 2 (17): 514-515. DIXON, H. N. (1924): The Students handbook of British Mosses. 3. Ed. London. EYTHORSSON, J. (1951): Jokla mys. Journal of Glaziology 1 (9): 502-503. HEDBERG, O. (1964): Features of afroalpine plant ecology. Acta phytogeographic a suecica 49: 1-144. HORIKAWA, Y. (1960): "Moss ball" of Jungermannia pallida in a sulphureous stream at Kusatsuonsen. Hikobia 2 (2): 125. HLCSTLEY, J. (1971): Vegetation In: E. VAN ZINDEREN-BAKKER, J. WINTERIWTTOM, R. DYER (Edit.): ::\{arion and Prince Edward Islands: 98-159. Cape Town. IWATSUKI, Z., TAKITA, K., & GLINE, J. (1983): Moss balls of Lake Kutcharo, Hokkaido. Miscellanea bryolog. et lichenolog. 9 (9): 199-201. JAMES, Th. P. (1875): List of mosses from the southern part of Kerguelen Island. Bull. of the Torrey bot an. Club 6 (9): 54-55. _ (1876): l\Iusci. In: J. H. KIDDER: Contributions to the natural history of Kerguelen Island. Bull. of the United States nation. Museum 3: 25-27. LID, J. (1938): Mosbollar. Nytt Magasin for Naturvidenskapene 78: 101-104. MAGDEFRAU, K. (1982): Life forms of Bryophytes. In: A. J. E. SMTIH (Edit.): Bryophyte Ecology, 45-58. Chapman & Hall, London-New York. MARTIN, 'Y. (1952): Unattached mosses in the New Zealand flora. Bryologist 55: 65-70. MITTEN, W. (1879): Musci of Kerguelen's Land. Philosoph. Transact. of the Roy. Soc. Lodon 168 (Extra volume): 24-39. MULLER, K. (1883): Die auf der Expedition S. M. S. Gazelle von Dr. Naumann gesammelten Laubmoose. ENGLER's Botan. Jahrbiicher 5: 76-88. (1889): Laubmoose. Forschungsreise S. M. S. Gazelle, 4. Teil (Botanik) Nr. 5: 1-64. Berlin. (1890): Bryologia Austro-Georgiae. Die internationale Polarforschung 1882-83, Die deutschen Expeditionen (Edit. GEORG NEUMAYER) 2: 279-322. Hamburg. OCHI, H. (1956): Moss ball from the Lake Kutcharoko. Miscellanea bryolog. et lichenolog. 1 (3): 3. (Japanese, Engl. translation. In: SHACKLETTE 1966, p. 348). OSADA, T. (1956): Bryophyta from Tarutana sulphureous spring. Miscellanea bryolog. et lichenolog.
1 (3): 3-4. POTIER DE LA VARDE, R. (1955): Mousses recoltees ar::\'£. Ie Dr. Olov Hedberg en Afrique orientale. Arkiv for Botanik 3 (8): 125-204 (Stockholm). SCHENCK, H. (1905): Vergleichende Darstellung der Pflanzengeographie der subantarktischen Inseln. :VIit Einfiigung hinterlassener Schriften A. F. W. SCHIMPER'S. Wissenschaftl. Ergebnisse der deutschen Tiefsee-Expedition "Valdivia", 2, I: 1-178. Jena. SHACKLETTE, H. T. (1966): Unattached moss polsters on Amchitka Island. Bryologist 69: 346-352. TAKAKI, N. (1956): Moss ball found on the summit of Mt. Ontake, Kiso. Miscellanea bryolog. et lichenolog. 1 (3): 1-2. TAKAKI, N. (1958): The bryophyte vegetation of Ontake Mountain, central Japan. Jour. Hattori Bot. Lab. 20: 245-271. WERTH, E. (1906): Die Vegetation der subantarktischen Inseln Kerguelen. Possession- und HeardEiland. 1. Teil. Deutsche Siidpolar-Expedition 1901-03 (Ed. E. VON DRYGALSKI), 8 (1): 155-176. Berlin. Received July 18, 1985 Authors' addresses: Prof. Dr. ERWIN BECK, Botanisches Institut der Universitat Bayreuth, Postfach 3008, D - 8580 Bayreuth; Prof. Dr. KARL MAGDEFRAU, WaldstraJ.le 11, D - 8024 Deisenhofen bei Miinchen; Dr. MARGOT SENSER, Botanisches Institut der Universitat J\Hinchen, Menzinger StraJ.le 67, D - 8000 Miinchen 19.
Globular Mosses ERWIN BECK, KARL MAGDEFRAU and MARGOT SENSER
Abstract On bare soils, subjected to subarctic climate conditions, lenticular to spherical moss balls have been observed which were completely unattached to the substratum, This article summarized the present knowledge on this unique life-form of foliar mosses, starting with a short treatise on the history of discovery. Then the geographical distribution of globular mosses on the subantarctic islands, the subarctic regions and in the temperate zone is reported. Abundantly, moss balls occur in the alpine zone of high mountains in tropical Africa, especially on Mt. Kenya. A taxonomic approach (Table 1) revealed that globular mosses are representatives of acrocarpous genera which usually form dense hemispherical cushions. As shown by the material from Mt. Kenya [Grimmia ovalis (HEDW.) LINDB.] the globoid shape originates by continual motion either of fragments of moss cushions which have been ruptured by frost or of single moss plants or small aggregations thereof which form a loose carpet on otherwise bare soil. Wind and solifluction which is due to nocturnal needle-ice formation and thawing of the soil in the day time could be demonstrated by two field experiments as moving forces. Structural analysis of the 0.5 to 8 cm large balls of Grimmia ovalis showed three zones: The outer layer of living parts is followed by a zone of morphologically intact but dead sections of the plants while the core consists of a peaty material composed of disintegrated leaflets, rhizoids and stems and of minute soil particles as well. The velocities of uptake of water and of methylene blue (as a model substance for cationic nutrients) into a spheroid of Grimmia ovalis has been determined under field conditions.
1. Introduction A special feature of plant life on bare soils of subarctic and high alpine regions which are subjected to vigorous frost heaving and solifluction is the occurrence of thalli of algae and lichens and of cushions of mosses which are not attached to the substrate. Under certain circumstances the latter can develop a lenticular or even completely spherical shape (Fig. 1) and thus have been referred to as globular or spherical mosses or moss balls. Taxonomical work on this specialized life-form has revealed that the capability of developing unattached globes is not confined to a single species or family but was aquired by a variety of mosses which in other habitats form attached cushions.
2. Discovery of globular mosses On the occasion of the transit of Venus in December 1874 the U.S. sent an observation expedition to Kerguelen Island. The Surgeon, J. H. KIDDER, availed himself of collecting plants especially at the southern part of the island. Among 28 species of mosses, which were identified by Th. P. JAMES, were two new species of Grimmia. One of these, G. kiilderi, was described as "compacte globosa pulvinata" (JAMES 1875, 1876) and an ecological observation on this species was added: "The small balls formed by this curious moss seem not to be rooted to another plant, but to be blown about by the wind indiscriminately ... Very local". When in 1898 the German deep sea research expedition "Valdivia" disembarked at Kerguelen Island, the botanist A. F. W. SCHIMPER, too, observed the globular mosses, and without knowledge of 6
Flora, Bd. 178
E. BECK et al. Tab)P 1. Compilation, taxonomieal affiliation and provenance of foliar mosses which have been reported to form globoids. An asterisk indicates an illustration in the reference Family jSpccies
Locality
Reference
Kerguelen Island Prince Edward Island Marion Island
SCHENCK 1905* HUNTLEY 1971* H. HERTEL, Botan. Staatssamml. Mu· nich Nr. 24126a
Norway Alaska
LID 1938* BENNINGHOFF 1955
Kerguelen Island Alaska Prince Edward Island
SCHENOK 1905* BENNINGHOFF 1955 HUNTLEY 1971*
Jan Mayen Marion Island Jan Mayen
LID 1938 HUNTLEY 1971 * LID 1938*
Mt. Ontake, Japan Norway Kerguelen Island
TAKAKI 1956, 1958 LID 1938* JAMES 1875
Mt. Elgon, Kenya
HEDBERG 1964*
Mt. Kenya, Kenya Mt. Kilimanjaro, Tanzania
HEDBERG 1964* POTIER DE LA V ARDE 1955 leg. E. BECK 1979, det. M. BrZOT
Andreaeaceae
Andreaea parallela C. MB"ELL. - regularis C. ::\1B"ELL.
-
rupestris HEDW. (= A. petrophila EHRH.)
Ditrichaceae
Ditrichum conicum (MONT.) MITT. (= Blindia aschistodontoides C. i\IuELL.) - flexicaule (SCHWAEGR.) HAM - strictum (H. HOOK et WILS.) HAM Dicranaceae
Dicranoweisia crispula (HEDw.) MILDE Holodontium pumilum (MITT.) BROTH. Kiaeriafalcata (HEDw.) HAGEN Grimmiaceae
Grimmia decalvata CARD. - donniana SM. - kidderi JAMES - laevigata BRID. (= G. campestris BUROHELL) ovalis (HEDw.) LINDB. (= G. commutata HUEB., G. ovata WEB. et MOHR)
Mt. Kenya, Teleki Valley
Rhacomitriumfasciculare (HEDw.) BRID.
Breidamerkurjokull, Island
- sudeticum (FUNCK) B.S.G. Schistidium apocarpum (HEDW.) B.S.G.
Norway Amchitka Island, (Aleutian Islands)
EYTHORSSON 1951, cf. SHAOKLETTE 1966 LID 1938* SHACKLETTE 1966*
the former publication by JAMES, described them on the basis of photographs (SCHENCK 1905) as follows (translated): "The most marvellous forms of mosses in the Azorella formation are represented by the species designated as globular mosses, their diameter varying between that of a cherry and a middle-sized potato. The smaller balls are formed by Blindia aschistodontoides, the larger ones, however, by Andreaea parallela, the stems of which regularly radiate from a central core of soil or a pebble. Strong winds roll these bodies over large distances; similar to other wind-blown structures they concentrate at certain places until a gust of wind again blows them away. Thus, successively the different faces are exposed and are able to develop."
Globular Mosses
75
3. Distribution of globular mosses 3.1. Subantarctic regions Even at the place of detection, on Kerguelen Island, globular mosses occur only on special sites what was commented by JAMES by the term "very local". Therefore it is not surprising that this life-form was not included in the comprehensive records of mosses of that island established by the British "Venus Expedition" (MITTEN 1879), the German "Gazelle-Expedition 1874~76" (MULLER 1883, 1889) and on the occasion of the "International Polar Research 1882~83" (MULLER 1890). E. WERTH, an excellent observer who studied the vegetation of Kerguelen Island for 15 months during the "Deutsche Sudpolar Expedition 180l~3" wrote: "Globular mosses as collected and described by SCHIMPER could never be observed by us (1906)". According to HUNTLEY (1971) moss balls occur on other subantarctic islands, too, namely on Marion and Prince Edwards Island: "Several moss species besides occuring as small cushions and buttons, develop a spherical shape in certain localities. Balls of one to ten centimetres diameter of Holodontium pumilum, Andreaea spp. and Ditrichum strictum were especially abundant on fieldmark on Prince Edward Island ... The frequency of fluctuations across freezing point on the Marion and Prince Edward Island may be sufficient to produce moss balls". H. HERTEL (Munich), in 1982, collected globes of Anareaea regularis (Botanische Staatssammlung, Munchen Nr. 24126a) at the N-coast of Marion Island and commented: "Only a small percentage of the moss balls was found to be completely unattached; the majority are attached to the substratum forming 3/4 to 5/6 spheres". Similarly, Ditrichum strictum (det. R. OCHYRA) was found by him as globoid. From the bryologically well investigated South Georgia, spherical mosses have not yet been reported, although those species which produce this life-form on Kerguelen, Prince Edward and Marion Islands, are present. 3.2. Subarctic regions From subarctic areas subjected to similar climatic conditions as the subantarctic, globular mosses have been reported, too. LID (1938) observed so-called "mossbollar" of Kiaeriafalcata and Dicranoweisia crispula on Jan Mayen (between Iceland and Spitzbergen) and of Rhacomitrium suaeticum, Andreaea rupestris and Grimmia aoniana in the alpine regions of Norway. SHACKLETTE (1966) found "unattached moss polsters" of Schistiaium apocarpum at Amchitka Island (Aleutian Islands). The socalled "J6klamys" (glacier mice) occuring on Iceland (EYTHORSSON 1951) and in the area of the Matanuska-glacier (Central Alaska; BENNINGHOFF 1955), representing pebbles which are completely covered by mosses (Anareaea rupestris, Ditrichum flexicaule) may also be grouped into this category. 3.3. High mountains of the temperate zone Up to the present, globular mosses have only been found in one place of the Eurasian Mountains, namely on Mt. Ontake in Central Japan (TAKAKI 1956, 1958). Close to the top (at an altitude of 3,100 m) Grimmia aecalvata produces spheroids of 0.5 to 1.0 em in diameter. 3.4. Afroalpine regions OLOV HEDBERG (1964), the investigator of the alpine vegetation of the East African high mountains, when participating in the "Swedish East African Expedition 1948" detected globular mosses on solifluction soils at the Western slopes of Mt. Kenya at an altitude of 4,200 m and on Mt. Elgon at 4,300 m. POTIER DE LA V ARDE (1955) identified these specimens as Grimmia campestris and G.ovata, respectively.
o·
7G
E.
BECK
et al.
He cOlllmented on the latter "Les touffes presentent sous la forme de balles spheriques, n'avant aucune adherence avec Ie substratum". Two of the authors of this article, in 1979 and 1980 were able to collect a bulk of material at Mt. Kenya (Teleki Valley 4,000-4,500 m altitude) which provided the basis for the structural studies described in chapter 6. Globular mosses (Grimmia ovata) have also been recorded from the East side of Mt. Kilimanjaro (HEDBEBG 19(4); they occur on the western slopes of Kibo, too, at an altitude of 4,600 to 4,800 m. From the Andes, the occurrence of moss balls has not yet been reported. However, according to similarity of climatic and edaphic conditions, this life form could very well exist at altitudes above 4,000 m.
4. Taxonomic affiliation of globular mosses Globular mosses consistently belong to acrocarpous families of leafy mosses; they are representatives of genera which usually form dense hemispheric cushions (MAGDEFRAU 1982). Table 1 provides a survey of the species recorded up to the present as to form balls or globoids.
5. Origin of the globoid shape In the Afroalpine region of Mt. Kilimanjaro (Tanzania), Mt. Elgon and especially of Mt. Kenya (both Kenya) globular mosses are found regularly in areas which are subjected to considerable soil movement due to needle ice formation and solifluctien. These phenomena were usually observed on horizontally layered or gently slopir:g bare soils which contain sufficient water to enable ice crystals to be formed duril~g the nocturnal frost period. According to the literature the formation of a moss globoid commences with the fragn:entation of a moss cushion and detachment of small portions or even single plants thereof from the substrate. Heavy winds (AUBERT DE LA RUE 1968; SHACKJ,ETTE 1966; JAMES 1875), frost rupture (HEDBERG 19(4) or kicking by animals e.g. the caribou (STEERE, personal communication 1979) have been considered to be responsible for the disintegration of an attached moss cushion. In the Afroalpine regions disruption of moss cushions by frost is regularly found and quite obvious especially on rocky substrates (Fig. 2). The fragments are often observed downhill of moss-covered rocks; they are turned around by soil movement resulting in an allround growth, whereby the globoid shape gradually develops. However, because of the original hemispherical cushion profile, those moss balls never become ideal spheres but consistently show two or more differently developed portior:s (Fig. 3). This type represents the moss balls found predominantly on sloping solifluction soils. On the contrary, spherical moss balls are regularly observed in great numbers on horizontal soils exhibiting various types of the so-called solifluction polygons. On such localities moss cushions were found predominantly inside and at the edge of Festuca tussocks. Single stems rather than larger fragments become separated from the cushicns probably due to frost rupture combined with the grating motion of the grass blades. As a consequence, single moss plants or small aggregations thereof were found to form a loose carpet from which spherical moss balls develop by branching ard continual motion (Fig. 4). Due to increasing immobility the large balls apparently rest for longer periods on the same side and thus flatten with time. Two environmental factors are responsible for the motion of the moss balls, namely solifluction and wind. In an experiment performed at Teleki Valley (Mt. Kenya) at an altitude of 4,200 m the effect of both factors was studied. Moss balls were labelled
77
Globular Mosses
Fig.!. Moss balls of Grimmia ovalis on gently sloping soil at Teleki Valley (l\It. Kenya) at an altitude of 4,300 m. (Foto E. BECK, March 1983). Fig. 2. Disruption by frost of cushions of Grimmia ovalis growing on rock peak, 4,600 m altitude; Foto E. BECK, March 1980).
PIt.
Kenya, Hiilnel
Fig. 3. Moss ball which has originated from a fragment of a cushion and thus shows differently developed faces (Mt. Kenya, Castle Rock, 4,500 m, Foto K. LIEDL, March 1980).
, 78
E.
••• •• •• '..* • •• • •• • .... • - • ~
~
~
BECK
et al.
E () L.n
79
Globular Mosses
C)
----~
/
110 -410.1980 4.10. -1110.1980
E
~ ___ ------------------------_____-8 8
Fig. 5. Dislocation and movement of globular mosses by solifluction and wind on a horizontal area. Size and shape of the moss-balls are true to scale. The spheroids were labelled at the beginning of the experiment by a thread drawn diametrically through the core. 19.2.85 -13.1985 -631985 80 cm ---....------;-,
N
,-...----><----
x
x
E
W .:;
x
E
x
co
900
Cft Festuca pilgeri tussock
Fig. 6. Movement of globular mosses by solifluction alone on a horizontal area protected from wind. Other conditions as in legend of Fig. 5.
Fig. 4. Collection of moss balls from a horizontal area of bare soil showing the development of the spherical shape from single stems (Mt. Kenya, Teleki Valley, 4,200 m; Foto K. LIEDL, March 1980).
80
E.
BECK
et al.
in their natural habitat with a thread, one end of which was marked and the location of the globes was sketched into a diagram. After periods of 4 and 11 d, respectively, the situation and orientation of the mosses was analyzed. The results are shown in Fig. 5. Only one out of fourteen balls was found unchanged. All others had been turned and (or) removed from their original position. The data do not show a correlation between the size of the ball and the extent of movement. In this experiment both factors, wind and solifluction have affected the situation of the mosses. In another experiment the effect of wind was excluded by protection of a similar area by a stonewall. The experiment was started in the dry season. Due to dryness of the soil solifluction was not observed and consequently the mosses kept their position. Subsequently the area was then watered daily. Considerable solifluction resulting in the formation of gravel polygons occurred after a few nocturnal frosts and the moss balls started toturn around (Fig. 6) but remained close to their original position on the field. Expectedly the smaller balls appeared to turn somewhat faster than the larger ones. From these experiments it is obvious that wind is responsible for the dislocation of the moss balls while solifluction alone would only turn the globoids around. Although there is wind all year in the Afroalpine zone, its effect is mainly observed during the dry season when the moss balls are dry, since the weight of the wet balls would be too heavy for movement by an air stream. On the other hand growth of the mosses requires humidity and thus preferentially takes places under conditions where also needle-ice formation and solifluction occur.
6. Structure of globular moss balls The diameter of the moss spheres of Grimmia ovalis varies between 0.5 and 5.5 cm; larger specimens (6 to 8 cm), however, independently of their mode of origin are of discoid shape exhibiting two flanks of preferential reclining while the margins represent the main areas of growth. JAMES (1875, 1876) reported the globes of Grimmia kidderi to be "found only in a barren state": Similarly, the spheres of Grimmia oval is do not develop sporophytes, although the attached cushions of this speces, even those found on rocks amongst the balls, are copiously fertile. Obviously the rolling motion of the globes impedes thriving of the spore cases. The latter, however, have been observed on large discoids. Apparently these balls, due to their relative immobility rest sufficiently long on one flank to enable development of sporophytes at the margins. Independently of the mode of origin, the stems in a moss ball of Grimmia ovalis show radial growth from a central core of soil-like material. As is evidenced by the ample material of Grimmia oval is from Mt. Kenya (110 specimens) the structure of the globular cushions is similar to that of the hemispherical, attached tufts. Both types, by basitonic as well as acrotonic innovation stems likewise extend in length and width (Fig. 7). Heterophylly is pronounced in the globular form of Grimmia ovalis to a similar extent as in attached cushions. It is remarkable that the density of the rhizoids increases towards the center of the spheroid. The outer layer which is formed by the green parts of the plants usually does ot exceed a thickness of 6 mm. Towards the center it is followed by a brownish layer of dead, however still morphologically intact sections. The innermost portion of the spheroid, the soil-like material, consists of fragments of leaflets, stems and especially rhizoids and thus resembles a moss peat. In particular the plant sections of the second, brownish layer show a cover of mineral dust and consequently minute mineral grains are also detectable in the peaty material of the core. Obviously, soil dust is continuously blown into the globoid and then adheres to the plant surface and thus might contribute to the mineral nutrition of the moss.
1
81
Globular Mosses
B Fig. 7. Grimmia oval is (HEDW.) LINDB. A. Acrotonic and basitonic branching of a stem isolated from a spherical moss ball of 2.5 cm dia· meter. B. Stem with sporogon and calyptra from the edge of a large discoid moss ball (Fig. 4, lower row, at the right).
Sometimes moss balls contain a larger portion of sand or even a small stone in their center. Apparently such globoids originate from a larger fragment of an attached cushion which upon disintegration kept contact to a loose piece of substratum. In the temperate regions an analogous formation of a moss ball may occur but rather casually and only from a species producing dense tufts (MAGDEFRAU 1982). If by exogenous forces parts of tufts or young portions thereof were teared away and turned upside down, innovation stems can develop on the original lower side. Movement of such tuft fragments by wind could then result in the formation of discoidal, ellipsoidal and even spherical moss balls. "Spheroidal balls" of Leucobryum glaucum, "entirely unattached" were described in DIXON's handbook (1924) and have been observed recently by Prof. Dr. W. PROBST near Flensburg (F.R.G.) in a forest which is exposed to heavy winds (peronal communication 1982). Under certain circumstances, pleurocarpous mosses, too, are able to survive for a while after having been separated from their substratum, as has been reported by DIXON (1924) for Thamnium alopecurum (Great Britain) and by MARTIN (1952) for Echinoaium hispiaum (New Zealand). However, such unattached mosses are not comparable to the globular life form described in this article. Unlike Grimmia, unattached specimens of both species differ in habit, size, mode of branching and number of branches from the normal form (MARTIN 1952) and are found rather as discoids than as globoids. Similarly, the so-called moss balls of Jungermannia pallida (HORIKOWA 1960) and of Leptodictyum riparium (OeHI 1956) which have been observed in lakes and creeks of Japan (OSADA 1956, IWATSUKI et al. 1983) do not represent globular mosses in the true sense: They are comparable to the "sea balls" which are well known to originate from algae or even dead plant material (e.g. Posiaonia fibres) by the rolling forces of the waves.
II. II
E.
BECK
.lile• • • •==.·!!!!!II!!!!!!!!!!!I!!!!!!!!!!!!!!!!!!!!!!'!!!!!!!!!:i!!
et a1.
A Fig. SA. Cross section of a moss-ball which has been sitting for three days on methylen blue powder (xx) in its natural habitat. Stained areas are indicated by thick lines and dots. Those parts which were still green (lines) and brown (dots), respectively , are drawn by thin symbols. Revolution of the spheroid during the period is shown by the circular arrow. Fig. SB. Drawing of a single moss plant removed from the indicated area of the moss ball shown in A. Thick lines and dots show the stained parts.
7. Uptake of nutrients and water Direct uptake of water and dissolved nutrients by those leaflets which are in direct contact with the soil appears to be very probable. The results of the followinge xperiment confirm this assumption : A moss spheroid was put into moist soil to which a few grains of methylen blue had been added and the distributio n of the dye in the ball was analyzed after 3 d (Fig. SA). During that period the moss ball had turned about 90° and two thirds of the spheroid were stained. All those plants which had been in contact with the dye were completely blue. One of the stems which had not directly been in contact with the dye was investigate d microscopi cally. Only two of the green leaflets (probably growing leaflets) showed blue tips (Fig. SB). However, the stem, the whole felt of the rhizoids, the older brownish leaflets and two shootlets were completely stained. Thus it appears that the dissolved dye has been taken up into the central core from which it entered the dead parts of the plants by capillary forces. From there it had been transporte d to the growing regions of the stem. Methylene blue at the existing pH-value represents a monovalen t cation and thus should strongly be adsorbed by the cell wall material of the moss which is thought to be negatively charged. This ionic interaction might be responsible for the relatively slow spreading of the dye over the moss ball as compared to water. Even if only one edge of the globoid was watered, the whole ball was found to be wet after a few minutes.
Acknowledgement The field work waS conducted during several expeditions devoted to the project "Ecological Research on AfroaJpine Flowering plants" supported by the Deuteche Forschungsg emeinschaft .
Globular Mosses
83
The authors wish to thank the Kenyan authorities for the permlsslOn to conduct research at Mt. Kenya National Park. They are grateful to Dr. R. SCHEIBE, University of Bayreuth, for assistance with some of the field experiments.
References AUBERT DE LA RUE, E. (1968): Balles des mousses vagabondes, curiosites vegetilJes des iles Kerguelen. Terres australes et antarctiques francaises 45: 3-9. Paris. BENNINGHOFF,1\1. S. (1955): Joklamys. Journal of Glaziology 2 (17): 514-515. DIXON, H. N. (1924): The Students handbook of British Mosses. 3. Ed. London. EYTHORSSON, J. (1951): Jokla mys. Journal of Glaziology 1 (9): 502-503. HEDBERG, O. (1964): Features of afroalpine plant ecology. Acta phytogeographic a suecica 49: 1-144. HORIKAWA, Y. (1960): "Moss ball" of Jungermannia pallida in a sulphureous stream at Kusatsuonsen. Hikobia 2 (2): 125. HLCSTLEY, J. (1971): Vegetation In: E. VAN ZINDEREN-BAKKER, J. WINTERIWTTOM, R. DYER (Edit.): ::\{arion and Prince Edward Islands: 98-159. Cape Town. IWATSUKI, Z., TAKITA, K., & GLINE, J. (1983): Moss balls of Lake Kutcharo, Hokkaido. Miscellanea bryolog. et lichenolog. 9 (9): 199-201. JAMES, Th. P. (1875): List of mosses from the southern part of Kerguelen Island. Bull. of the Torrey bot an. Club 6 (9): 54-55. _ (1876): l\Iusci. In: J. H. KIDDER: Contributions to the natural history of Kerguelen Island. Bull. of the United States nation. Museum 3: 25-27. LID, J. (1938): Mosbollar. Nytt Magasin for Naturvidenskapene 78: 101-104. MAGDEFRAU, K. (1982): Life forms of Bryophytes. In: A. J. E. SMTIH (Edit.): Bryophyte Ecology, 45-58. Chapman & Hall, London-New York. MARTIN, 'Y. (1952): Unattached mosses in the New Zealand flora. Bryologist 55: 65-70. MITTEN, W. (1879): Musci of Kerguelen's Land. Philosoph. Transact. of the Roy. Soc. Lodon 168 (Extra volume): 24-39. MULLER, K. (1883): Die auf der Expedition S. M. S. Gazelle von Dr. Naumann gesammelten Laubmoose. ENGLER's Botan. Jahrbiicher 5: 76-88. (1889): Laubmoose. Forschungsreise S. M. S. Gazelle, 4. Teil (Botanik) Nr. 5: 1-64. Berlin. (1890): Bryologia Austro-Georgiae. Die internationale Polarforschung 1882-83, Die deutschen Expeditionen (Edit. GEORG NEUMAYER) 2: 279-322. Hamburg. OCHI, H. (1956): Moss ball from the Lake Kutcharoko. Miscellanea bryolog. et lichenolog. 1 (3): 3. (Japanese, Engl. translation. In: SHACKLETTE 1966, p. 348). OSADA, T. (1956): Bryophyta from Tarutana sulphureous spring. Miscellanea bryolog. et lichenolog.
1 (3): 3-4. POTIER DE LA VARDE, R. (1955): Mousses recoltees ar::\'£. Ie Dr. Olov Hedberg en Afrique orientale. Arkiv for Botanik 3 (8): 125-204 (Stockholm). SCHENCK, H. (1905): Vergleichende Darstellung der Pflanzengeographie der subantarktischen Inseln. :VIit Einfiigung hinterlassener Schriften A. F. W. SCHIMPER'S. Wissenschaftl. Ergebnisse der deutschen Tiefsee-Expedition "Valdivia", 2, I: 1-178. Jena. SHACKLETTE, H. T. (1966): Unattached moss polsters on Amchitka Island. Bryologist 69: 346-352. TAKAKI, N. (1956): Moss ball found on the summit of Mt. Ontake, Kiso. Miscellanea bryolog. et lichenolog. 1 (3): 1-2. TAKAKI, N. (1958): The bryophyte vegetation of Ontake Mountain, central Japan. Jour. Hattori Bot. Lab. 20: 245-271. WERTH, E. (1906): Die Vegetation der subantarktischen Inseln Kerguelen. Possession- und HeardEiland. 1. Teil. Deutsche Siidpolar-Expedition 1901-03 (Ed. E. VON DRYGALSKI), 8 (1): 155-176. Berlin. Received July 18, 1985 Authors' addresses: Prof. Dr. ERWIN BECK, Botanisches Institut der Universitat Bayreuth, Postfach 3008, D - 8580 Bayreuth; Prof. Dr. KARL MAGDEFRAU, WaldstraJ.le 11, D - 8024 Deisenhofen bei Miinchen; Dr. MARGOT SENSER, Botanisches Institut der Universitat J\Hinchen, Menzinger StraJ.le 67, D - 8000 Miinchen 19.