Diphyscium foliosum, from here.

Belongs within: Embryophyta.
Contains: Sphagnales, Andreaeaceae, Bryidae, Funariidae, Archidium, Dicranideae, Polytrichaceae.

The Bryophyta are the mosses, the largest living group of non-vascular land plants. Mosses are distinguished by the presence of distinct leaves and multicellular rhizoids on the gametophyte (which is the dominant part of the life-cycle, supporting the dependent sporophytes), and of a columnella (a cylinder of sterile cells) within the spore capsule (De Luna et al. 2003). Within the mosses, all authors support a division between the basalmost Sphagnopsida and the remaining mosses, with the Polytrichopsida and Bryopsida together forming a clade distinguished by a spore capsule opening through an operculum rather than dehiscently as in more basal forms. Sphagnopsida are represented in the modern flora by the genera Sphagnum and Ambuchanania; Ambuchanania leucobryoides is a rare species found growing in sandy washes in a small number of localities in Tasmania (Threatened Species Section, Tasmania, 2008).

The Andreaeopsida comprise a small assemblage of basal mosses in which the spores are released from the capsule via dehiscence through longitudinal slits, rather than via an operculum as in other mosses (Smith & Davison 1993). The monophyly of the Andreaeopsida is uncertain, with many authors regarding its members as a paraphyletic grade dividing the basal Sphagnopsida from the remaining mosses. The position of Takakia, a distinctive moss genus found in eastern Asia and north-west North America, has been particularly contentious, but it has been linked to Andreaeobryum by features such as the presence of secondary protonemata and of massed beaked mucilage-producing papillae. Takakia is otherwise distinguished by erect shoots arising from a stolon, terete leaves with oil droplets and slime hairs, and naked lateral gametangia. Species of Andreaeaceae are epilithic: Andreaea typically grows on granite or other acidic rocks while Andreaeobryum macrosporum grows on limestone (Flora of North America).

Polytrichopsida and Bryopsida are distinguished by the forms of the teeth around the capsule opening (forming the peristome): in Polytrichopsida, they are nematodontous (formed from entire cells) while in Bryopsida they are arthrodontous (formed from fragments of cell walls). Within the Bryopsida, the peristome comprises a single circlet of teeth in members of the subclass Dicranidae whereas members of other subclasses typically have a peristome of two circlets (reduced or lost in some taxa).

Rock mosses
Published 30 June 2014
Black rock-moss Andreaea rupestris, photographed by Sture Hermansson.

Upon first examining the picture above, you might think that you were looking at a patch of moss. Which would not be an unreasonable assumption to make, because that is exactly what you are looking at. But this is not just any moss, but perhaps one of the most interesting mosses out there.

The hundred or so species of the genus Andreaea, found in cooler regions around the world, are commonly known as rock mosses or granite mosses in reference to their preferred growth habitat on acidic rocks. They can often look black or red rather than green (presumably relative to how dry they are), and they are often brittle. Glime (2013) notes that a characteristic feature of granite mosses is that a hand brushed over one will come away with small fragments stuck to it, and suggests that this may act as a method of vegetative dispersal. Usually, granite mosses are autoicous: a single plant has both male and female reproductive structures, but they are borne in separate clusters. What makes Andreaea really interesting, though, is how it produces spores. Mosses produce spores from a sporophyte (diploid plant) that grows supported by the gametophyte (haploid plant) that comprises the green, vegetative stage of the moss life cycle. In most mosses, the sporophyte holds itself up by means of a long stalk called a seta, and spores are released from the terminal capsule by the ejection of a covering operculum.

Capsules of Andreaea, photographed by David Tng.

Andreaea does things differently. In this moss, the capsule is not supported by its own stalk, but is instead lifted up on an extension of the gametophyte called a pseudopodium. And instead of popping off an operculum, the Andreaea capsule splits open longitudinally into a squashed crown. Andreaea shows its difference after the spores are released as well: while the spores of other mosses germinate into a filamentous protonema (the moss ‘seedling’, as it were), the protonema of Andreaea bears thalloid appendages.

Such is the distinctive of Andreaea that it has been classified in a separate class from most other mosses, the Andreaeopsida. Phylogenetic analysis has demonstrated that Andreaea is one of the earliest diverging of all mosses, being the next to diverge from the main moss lineage after the Sphagnopsida (the group that includes Sphagnum). In some classifications, the class Andreaeopsida is restricted to Andreaea alone, but there are two other small genera that have been grouped with it in the past.

Andreaeobryum macrosporum, photographed by Masaki Shimamura.

Andreaeobryum macrosporum is a single unusual moss species found in north-west North America. Like Andreaea, it is found growing in rocks, though its preference is for basic rocks such as limestone. It also resembles Andreaea in having a spore capsule that opens through slits, though in the case of Andreaeobryum the apex of the capsule eventually wears off as well and the capsule splays fully open. The biggest difference between Andreaea and Andreaeobryum is that the capsule of the latter is not raised on a gametophytic pseudopodium, but possesses its own supporting seta like that of typical mosses (albeit a particularly short and stubby one). The phylogenetic position of Andreaeobryum remains uncertain: a molecular analysis by Chang & Graham (2011) recovered an AndreaeaAndreaeobryum clade, but with very low support.

Takakia lepidozioides, from here.

The real wild-card in basal moss phylogeny, however, is the little green monster known as Takakia. Takakia is a genus of two species found in western North America and eastern Asia. It was first discovered in the Himalayas and described in 1861—as a liverwort. This is a bit like being presented with a new species of snake, and describing it as a type of eel. But it has to be pointed out that Takakia possesses some very un-moss-like features. It has finely divided leaves, a feature common in liverworts but not known from any other moss. Its leaves contain oil bodies: again, unlike any other moss, but like many liverworts. Matters were not helped by the fact that Takakia was first described from vegetative material only, and it was not until the description of sporophytes in the 1990s that Takakia was conclusively accepted as a moss (Renzaglia et al. 1997).

Even so, its position within the mosses remained uncertain. A relationship with Andreaea has been suggested, as the capsule (though borne on a seta rather than a pseudopodium) opens through a single spiral slit. However, recent phylogenetic analyses have not supported a direct relationship between the two. Chang & Graham (2011) found in the analysis of their data that its position was vulnerable to the analytical model used: it could be placed as the sister taxon to all other mosses, or it could be the sister to the Sphagnopsida (with the two together being the basalmost moss clade). We have not heard the last of little Takakia.

Systematics of Bryophyta
<==Bryophyta [Bryophytina, Musci]WM14
    |    |--SphagnalesD24
    |    `--Ambuchanania Seppelt & Crum 1999 [Ambuchananiaceae, Ambuchananiales]SK02
    |         `--A. leucobryoides (Yamaguchi, Seppelt & Iwats.) Seppelt & Crum 1999 (see below for synonymy)SK02
    `--Bryatae [Acrocarpineae]C-S98
         |  i. s.: Eustichia [Eustichiaceae]D03b
         |           `--E. longirostrisD03b
         |    |--AndreaeaceaeFHH01
         |    |--Takakia [Takakiaceae, Takakiales, Takakiidae]FHH01
         |    |    `--T. ceratophyllaFHH01
         |    `--Andreaeobryum [Andreaeobryales, Andreaeobryopsida, Andreaeobryidae]OZB-O03
         |         `--A. macrosporumOZB-O03
         `--+--Bryopsida [Acrocarpae, Aplolepideae, Arthrodonteae, Diplolepideae, Mnionopsida]SK02
            |    |--BryidaeOZB-O03
            |    |--FunariidaeOZB-O03
            |    |--ArchidiumOZB-O03
            |    |--DicranideaeS04
            |    `--DiphysciidaeOZB-O03
            |         |--MuscoflorschuetziaOZB-O03
            |         |--TheriotiaOZB-O03
            |         `--Diphyscium Mohr 1803 [Diphysciaceae, Diphysciales]SK02
            |              |--D. foliosum (Hedw.) Mohr 1803S04 (see below for synonymy)
            |              |    |--D. f. var. foliosumD24
            |              |    `--D. f. var. acutifoliumD24
            |              `--D. mucronifolium Mitt. 1855SK02
            `--Polytrichopsida [Nematodonteae]SK02
                 |--Buxbaumia Hedw. 1801SK02 [Buxbaumiaceae, Buxbaumiae, Buxbaumiales S04, Buxbaumiidae, Buxbaumiineae]
                 |    |--B. aphylla Hedw. 1801SK02 [incl. B. vulgarisOZB-O03]
                 |    |--B. colyerae Burges 1932SK02
                 |    |--B. piperiFHH01
                 |    |--B. tasmanica Mitt. 1859SK02
                 |    |--B. thorsborneae Stone 1983SK02
                 |    `--B. viridis (Moug. ex DC) Brid. ex Moug. & Nestl. 1823 [incl. B. indusiata]S04
                 `--Tetraphidales [Tetraphididae, Tetraphidiineae]SK02
                      |--Oedipodium Schwägr. 1823 [Oedipodiaceae]S04
                      |    `--O. griffithianum (Dicks.) Schwägr. 1823S04 [=Bryum griffithianumD24]
                           |--Tetraphis Hedw. 1801S04
                           |    |--T. geniculataD24
                           |    `--T. pellucida Hedw. 1801S04 (see below for synonymy)
                           `--Tetrodontium Schwägr. 1824S04
                                |--T. brownianum (Dicks.) Schwägr. 1824S04 (see below for synonymy)
                                `--T. repandum (Funck) Schwägr. 1824S04 (see below for synonymy)
Bryophyta incertae sedis:
  Palamocladium leskeoidesPK03
  Sporogonites [Sporogonitales]BC98
    |    |--T. auriculataB-OO10
    |    `--T. serrulataN02
    `--Duthiella declinataN02
  Catharomnion Hooker & Wilson 1854SK02
    `--C. ciliatum (Hedw.) Wilson 1854 [=Hypopterygium ciliatum]SK02
  Cladomnion Hooker & Wilson 1854SK02
    |--C. ericoides (Hooker) Wilson 1854SK02
    `--C. gracileD03a
  Cyrtopus (Brid.) Hooker 1867SK02
    `--C. setosus (Hedw.) Hooker 1867 [=Anictangium setosum, Cladomnion setosum, Garovaglia setosa (n. n.)]SK02
  Mniomalia Müll.Hal. 1874SK02
    `--M. semilimbata Müll.Hal. 1874SK02
  Streblotrichum Palisot de Beauvois 1804SK02
    `--S. bicolor (Bruch & Schimp.) Loeske 1909 [=Barbula bicolor, Gymnostomum bicolor]SK02
  Acanthocladium macgregoriiSK02
  Chrysocladium phaeumSK02
  Phyllogonium [Phyllogoniaceae]J87
    `--P. fulgensJ87
  Prionodon [Prionodontaceae]J87
    `--P. densusJ87
  Pseudodistichium buchananiM49b
  *Bellia nervosaM49a
  Blindiopsis immersaM49a
  Sciadocladus menziesiiM49a
  Aporella Podps. 1916KC01
  Arbuscula Crum, Steere & Anderson 1964KC01
  Beccaria Müll. Hal. 1872KC01
  Braunia Bruch & Schimp. 1846KC01
  Cryptothecium Penz. & Sacc. 1897KC01
  Dozya Lacoste 1866KC01
  Drummondia Hook. 1828KC01
  Gymnocybe Fr. 1825 (nom. rej.) non Karst. 1879KC01
  ‘Leratia’ Broth. & Paris 1909 non Pat. 1907KC01
  Microstelium Pat. 1899 (n. d.)KC01
  Schroeterella Herzog 1916KC01
  Sphaerangium Schimp. 1860KC01
  Venturiella Müll. Hal. 1875KC01
  Willia Müll. Hal. 1890KC01
  Hydropogon Bridel 1827OZB-O03
    `--H. fontinaloides [=Dryptodon fontinaloides]OZB-O03
  Ditrichopsis clausaB-OO10
  Pringleella sinensisB-OO10
  Shevockia inunctocarpaB-OO10
  Leptocladium sinsenseB-OO10
  Microctenidium assimileB-OO10
    |--L. gracileB-OO10
    `--L. robustumB-OO10
Nomen nudum: Cladomnium crenato-obtusum Dusén 1903D03a

Ambuchanania leucobryoides (Yamaguchi, Seppelt & Iwats.) Seppelt & Crum 1999 [=Sphagnum leucobryoides Yamaguchi, Seppelt & Iwats. 1990]SK02

Diphyscium foliosum (Hedw.) Mohr 1803S04 [=Buxbaumia foliosaOZB-O03; incl. Webera diphysciumOZB-O03, Mollia haggartiD24, Buxbaumia sessilisOZB-O03, Diphyscium sessileOZB-O03, Webera sessilisD24]

Tetraphis pellucida Hedw. 1801S04 [=Mnium pellucidumD24, Georgia pellucidaD24; incl. G. mnemosynumOZB-O03]

Tetrodontium brownianum (Dicks.) Schwägr. 1824S04 [=Bryum brownianumD24, Georgia brownianaOZB-O03, Tetraphis brownianaS04; incl. Tetraphis ovataOZB-O03, Tetrodontium brownianum var. rigidumOZB-O03, Tetro. variumOZB-O03]

Tetrodontium repandum (Funck) Schwägr. 1824S04 [=Tetraphis browniana var. repandaS04, Tetrodontium brownianum var. repandumOZB-O03; incl. Georgia ovataOZB-O03]

*Type species of generic name indicated


[BC98] Bateman, R. M., P. R. Crane, W. A. DiMichele, P. R. Kenrick, N. P. Rowe, T. Speck & W. E. Stein. 1998. Early evolution of land plants: phylogeny, physiology, and ecology of the primary terrestrial radiation. Annual Review of Ecology and Systematics 29: 263–292.

[B-OO10] Bednarek-Ochyra, H., & R. Ochyra. 2010. Bucklandiella shevockii (Bryophyta, Grimmiaceae), an exquisite new species from Yunnan, China. Polish Botanical Journal 55 (2): 499–506.

[C-S98] Cavalier-Smith, T. 1998. A revised six-kingdom system of life. Biological Reviews 73: 203–266.

Chang, Y., & S. W. Graham. 2011. Inferring the higher order phylogeny of mosses (Bryophyta) and relatives using a large, multigene plastid data set. American Journal of Botany 98 (5): 839–849.

[D24] Dixon, H. N. 1924. The Student’s Handbook of British Mosses 3rd ed. V. V. Sumfield: Eastbourne.

[D03a] Dusén, P. 1903a. The vegetation of western Patagonia. In: Scott, W. B. (ed.) Reports of the Princeton University Expeditions to Patagonia, 18961899 vol. 8. Botany pp. 1–34. The University: Princeton (New Jersey).

[D03b] Dusén, P. 1903b. Patagonian and Fuegian mosses. In: Scott, W. B. (ed.) Reports of the Princeton University Expeditions to Patagonia, 18961899 vol. 8. Botany pp. 63–126. The University: Princeton (New Jersey).

[FHH01] Frey, W., M. Hofmann & H. H. Hilger. 2001. The gametophyte-sporophyte junction: unequivocal hints for two evolutionary lines of archegoniate land plants. Flora 196: 431–445.

Glime, J. M. 2013. Bryophyta—Andreaeopsida, Andreaeobryopsida, Polytrichopsida. Chapt. 2-6. In: Glime, J. M. Bryophyte Ecology. Volume 1. Physiological Ecology. Ebook sponsored by Michigan Technological University and the International Association of Bryologists. Last updated 29 June 2013, available at

[J87] Judd, W. S. 1987. Floristic study of Morne La Visite and Pic Macaya National Parks, Haiti. Bulletin of the Florida State MuseumBiological Sciences 32 (1): 1–136.

[KC01] Kirk, P. M., P. F. Cannon, J. C. David & J. A. Stalpers. 2001. Ainsworth & Bisby’s Dictionary of the Fungi 9th ed. CAB International: Wallingford (UK).

[M49a] Martin, W. 1949a. The bryophytes of Stewart Island.—Part I. Transactions and Proceedings of the Royal Society of New Zealand 77 (2): 257–277.

[M49b] Martin, W. 1949b. Distribution of the mosses indigenous to New Zealand (supplement no. 1). Transactions and Proceedings of the Royal Society of New Zealand 77 (3): 355–360.

[N02] Negi, H. R. 2002. Abundance and diversity of moss communities of Chopta-Tunganath in the Garhwal Himalaya. Journal of the Bombay Natural History Society 99 (3): 418–433.

[OZB-O03] Ochyra, R., J. Żarnowiec & H. Bednarek-Ochyra. 2003. Census Catalogue of Polish Mosses. Institute of Botany, Polish Academy of Sciences: Cracow.

[PK03] Piippo, S., & T. Koponen. 2003. Review of the bryofloristic connections of New Guinea Island. Telopea 10 (1): 467–476.

Renzaglia, K. S., K. D. McFarland & D. K. Smith. 1997. Anatomy and ultrastructure of the sporophyte of Takakia ceratophylla (Bryophyta). American Journal of Botany 84 (10): 1337–1350.

[S04] Smith, A. J. E. 2004. The Moss Flora of Britain and Ireland 2nd ed. Cambridge University Press.

[SK02] Streimann, H., & N. Klazenga. 2002. Catalogue of Australian Mosses. Flora of Australia Supplementary Series 17. Australian Biological Resources Study: Canberra.

[WM14] Wickett, N. H., S. Mirarab, N. Nguyen, T. Warnow, E. Carpenter, N. Matasci, S. Ayyampalayam, M. S. Barker, J. G. Burleigh, M. A. Gitzendanner, B. R. Ruhfel, E. Wafula, J. P. Der, S. W. Graham, S. Mathews, M. Melkonian, D. E. Soltis, P. S. Soltis, N. W. Miles, C. J. Rothfels, L. Pokorny, A. J. Shaw, L. DeGeronimo, D. W. Stevenson, B. Surek, J. C. Villarreal, B. Roure, H. Philippe, C. W. dePamphilis, T. Chen, M. K. Deyholos, R. S. Baucom, T. M. Kutchan, M. M. Augustin, J. Wang, Y. Zhang, Z. Tian, Z. Yan, X. Wu, X. Sun, G. K.-S. Wong & J. Leebens-Mack. 2014. Phylotranscriptomic analysis of the origin and early diversification of land plants. Proceedings of the National Academy of Sciences of the USA 111 (45): E4859–E4868.

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