Archidium

 Archidium ohioense, photographed by Li Zhang.

Belongs within: Bryophyta.

Archidium is a genus of very small mosses typically found growing on soil in open sites. Capsules are sessile, spherical and cleistocarpous (Dixon 1924).

Characters (from Spence 2007): Plants mostly green. Stems terete, 1-20 mm. Leaves of distal portions of stems and of perichaetia ovate, ovate-lanceolate, linear-lanceolate to triangular, often reduced and distant in proximal portion of stem, flat or somewhat concave, apex acute to acuminate, sometimes incurved or rarely secund, margins plane, recurved or rarely incurved, distal margins smooth to finely serrulate; costa weak and not reaching apex or sometimes absent, to more often strong, single, percurrent to excurrent in a hairpoint; laminal areolation uniform to somewhat differentiated, cells mostly rectangular to rhomboidal, sometimes irregular in median and distal portions, rectangular and rhomboidal cells mixed with short sub-quadrate cells, alar cells similar to adjacent cells or differentiated, hyaline, wide-rectangular to quadrate. Sexual condition autoicous, paroicous or synoicous, antheridia often naked in axils of distal stem leaves or outer perichaetial leaves, sometimes enclosed in short shoots with small leaves (bracts). Perichaetial leaves often larger and more variable in shape than stem leaves, sometimes broadly ovate to elliptic. Capsule immersed in perichaetial leaves, brown or golden at maturity. Spores spherical to polyhedral, pale yellow to yellow-brown, golden, orange or red-orange, smooth to finely papillose.

<==Archidium Brid. 1826 [Archidiaceae, Archidiales, Archidiidae]SK02
    |--A. alternifolium (Dicks. ex Hedw.) Mitt. 1851S04 [incl. A. phascoidesD24, Pohlia tenerrimaD24]
    |--A. birmanicum Mitt. ex Dixon 1921SK02
    |--A. clarksonianum Stone 1997SK02
    |--A. clavatum Stone 1973SK02
    |--A. indicum Müll.Hal. 1888SK02
    |--A. minutissimum Stone 1985SK02
    |--A. ohioense Schimp. ex Müll.Hal. 1851SK02
    |--A. rehmannii Mitt. 1886SK02
    |--A. rothii Watts ex Roth 1914SK02
    |--A. stellatum Stone 1973SK02
    |--A. tenerrimumFHH01
    |--A. thalliferum Stone 1985SK02
    `--A. wattsii (Broth.) Stone 1984 [=Splachnobryum wattsii]SK02

*Type species of generic name indicated

References

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

[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.

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

Spence, J. R. 2007. Archidiaceae Schimper. In: Flora of North America Editorial Committee (eds) Flora of North America North of Mexico vol. 27 pp. 314–319. New York and Oxford.

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

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