Ectropothecium

Belongs within: Plagiotheciaceae.

Ectropothecium is a large and complex genus of about 200 species of mosses found around the world, with most species growing in water or completely waterlogged soil. Ectropothecium species possess one or a few inflated, hyaline alar cells, relatively elongate, slender setae, and very small, ovoid capsules that are horizontal to inclined and strongly constricted below the mouth when dry; they differ from members of the similar genus Hypnum in lacking a group of coloured alar cells (Moss Flora of China).

Mosses: not as simple as you think

Published 28 December 2009

I have to admit to becoming increasingly glad that I don’t work on mosses. Today’s subject is a moss, and looking up stuff on it has driven me into a strange world of unfamiliar terminology and fine-scale features. If I mess anything up here, I only hope that the legions of moss fans out there* forgive my transgressions.

*Do not doubt that they’re out there. As I’ve commented elsewhere, bryologists are a dedicated bunch.

Ectropothecium is a genus of mostly hydrophytic mosses found worldwide (hydrophytic plants grow either in water or in completely waterlogged soil; some Ectropothecium species do the former, others the latter). It belongs to a clade of mosses known as the pleurocarpous mosses; while other (acrocarpous) mosses branch only rarely and produce terminal archegonia (the female reproductive organs) at the end of the stem, pleurocarpous mosses produce lateral archegonia on highly branched and extensively interwoven stems (Shaw & Renzaglia 2004). Pleurocarpous mosses are divided molecularly into three orders, Ptychomniales, Hookeriales and Hypnales; Ectropothecium belongs to the Hypnales which have a smooth spore capsule with a calyptra (protective cap) that usually opens by splitting along one side (Buck et al. 2004). Within the Hypnales, Ectropothecium is placed in the family Hypnaceae; however, phylogenetic studies of Hypnales (e.g. De Luna et al. 2000) suggest that members of the Hypnaceae may be para- or polyphyletically placed within the order.

Ectropothecium itself is distinguished by having spore capsules that are very small (usually less than 1 mm long) and almost spherical (Buck & Tan 2008), non-decurrent leaves (not extending down the stem where they join), short and broad leaf cells and filamentous pseudoparaphyllia that are two or three cells wide at the base (Ireland 1992). Pseudoparaphyllia are small outgrowths of the stem that cluster around the base of new side-branches (as opposed to paraphyllia which are normally scattered more evenly along the entire stem); they may be thread- or blade-shaped. See Ignatov & Hedenäs (2007) for a review of the distinctions between paraphyllia, pseudoparaphyllia and proximal branch leaves, though to be honest if you understand the difference you’re somewhat ahead of me (as far as I can tell, pseudoparaphyllia grow on the stem around the primordium of a new branch and remain on the stem, while proximal branch leaves may start growing around the primordium but end up being transferred to the new branch).

Systematics of Ectropothecium

Characters (from Wu et al. 2005): Plants slender to rather robust, yellowish green or brownish green, glossy or not glossy. Stems prostrate, sometimes pendulous, ascending or erect when in dense mats, radiculose, simple or pinnately branched, branches ascending, usually complanate; paraphyllia absent, pseudoparaphyllia filamentous or lanceolate to foliose. Stem leaves and branch leaves heteromorphic, or more or less similar, ovate- or obovate-lanceolate, somewhat asymmetric, often falcate-secund, not decurrent at base, usually dorsal, ventral, and lateral leaves differentiated; costae double, short, very weak, or distinct; leaf cells linear, sometimes distinctly prorate; basal cells shorter and broader; alar cells few, small, quadrate or shortly rectangular, usually not particularly inflated, but with one or two cells clearly distinct. Autoicous or dioicous. Inner perichaetial leaves broadly lanceolate, gradually acuminate or suddenly narrowed to a slender acumen. Setae elongate; capsules horizontal to inclined, small to very small, ovoid to urceolate or shortly cylindrical, often constricted below the mouth when dry; exothecial cells sometimes mammillose; opercula inflated, conic, apiculate to shortly rostrate; annuli differentiated; peristome double; exostome teeth narrowly lanceolate, not bordered, cross-striate on the outer surface, trabeculate on the inner surface; endostome segments linear-lanceolate, with a high basal membrane and 2–4 cilia. Calyptrae cucullate, smooth, sometimes hairy. Spores small, usually smooth.

<==Ectropothecium Mitt. 1868SK02
    |--E. adnatumB57
    |--E. aneitense Brotherus & Watts 1915BW15
    |--E. bowiei Brotherus & Watts 1915BW15
    |--E. brachyphyllum Brotherus & Watts 1915BW15
    |--E. buitenzorgiiN02
    |--E. condensatum Broth. & Watts 1912SK02
    |--E. cyathotheciumB57
    |--E. cyperoidesN02
    |--E. gunnii Brotherus & Watts 1915BW15
    |--E. howeanum Broth. & Watts 1915SK02
    |--E. intorquatumBW15
    |--E. leptochaetonJ87
    |--E. leucochlorum (Hampe) Broth. 1908 (see below for synonymy)SK02
    |--E. longicauleB57
    |--E. micholitziiBW15
    |--E. molleB57
    |--E. moritzii Jaeger 1879SK02
    |--E. novae-valesiae (Broth.) Ireland 1992 [=Plagiothecium novae-valesiae Broth. 1916]SK02
    |--E. pacificumBW15
    |--E. percomplanatumB57
    |--E. riparioides Bartram 1952SK02
    |--E. sandwichense (Hooker & Arnott) Mitt. 1873 [=Hypnum sandwichense]SK02
    |--E. sodale (Sull.) Mitt. 1868SK02
    |--E. sydneyense Dixon 1950SK02
    |--E. umbilicatum (Müll.Hal.) Paris 1904 [=Hypnum umbilicatum]SK02
    |    |--E. u. var. umbilicatumSK02
    |    `--E. u. var. protractum (Müll.Hal.) Paris 1904 [=Hypnum umbilicatum var. protractum]SK02
    `--E. zollingeri (Müll.Hal.) Jaeger 1880 (see below for synonymy)SK02
Nomina nuda: Ectropothecium leptomyurum Paris 1900 [=Cupressina leptomyura Paris 1900]SK02
             Ectropothecium spirifolium Dusén 1903D03

Ectropothecium leucochlorum (Hampe) Broth. 1908 [=Drepanohypnum leucochlorum, Hypnum leucochlorum, Stereodon leucochlorus; incl. Plagiothecium howeanum Jaeger 1878 (n. n.), Hypnum howeanum (n. n.), P. howei (n. n.)]^SK02

Ectropothecium zollingeri (Müll.Hal.) Jaeger 1880 [incl. E. serrifolium, Glossadelphus serrifolius (Broth. & Watts) Broth. 1925]^SK02

*Type species of generic name indicated

References

[B57] Bartram, E. B. 1957. Additional Fijian mosses, III. Journal of the Washington Academy of Sciences 46 (12): 392–396.

[BW15] Brotherus, V. F., & W. W. Watts. 1915. The mosses of the New Hebrides [part 2]. Journal and Proceedings of the Royal Society of New South Wales 49 (2): 145–157.

Buck, W. R., C. J. Cox, A. J. Shaw & B. Goffinet. 2004. Ordinal relationships of pleurocarpous mosses, with special emphasis on the Hookeriales. Systematics and Biodiversity 2 (2): 121–145.

Buck, W. R., & B. C. Tan. 2008. A review of Elmeriobryum (Hypnaceae). Telopea 12 (2): 251–256.

De Luna, E., W. R. Buck, H. Akiyama, T. Arikawa, H. Tsubota, D. González, A. E. Newton & A. J. Shaw. 2000. Ordinal phylogeny within the hypnobryalean pleurocarpous mosses inferred from cladistic analyses of three chloroplast DNA sequence data sets: trnL-F, rps4, and rbcL. Bryologist 103 (2): 242–256.

[D03] Dusén, P. 1903. The vegetation of western Patagonia. In: Scott, W. B. (ed.) Reports of the Princeton University Expeditions to Patagonia, 1896–1899 vol. 8. Botany pp. 1–34. The University: Princeton (New Jersey).

Ignatov, M. S., & L. Hedenäs. 2007. Homologies of stem structures in pleurocarpous mosses, especially of pseudoparaphyllia and similar structures. In: Newton, A. E., & R. Tangney (eds) Pleurocarpous Mosses: systematics and evolution pp. 227–245. The Systematics Association Special Volume Series 71. Taylor & Francis/CRC Press: Boca Raton.

Ireland, R. R. 1992. Studies of the genus Plagiothecium in Australasia. Bryologist 95 (2): 221–224.

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

[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.

Shaw, J., & K. Renzaglia. 2004. Phylogeny and diversification of bryophytes. American Journal of Botany 91 (10): 1557–1581.

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

Wu P.-C., M. R. Crosby & S. He. 2005. Sematophyllaceae–Polytrichaceae. In: He, S. (ed.) Moss Flora of China. Science Press & Missouri Botanical Garden.