BFNA Title: Meesiaceae
Note October 27, 2009: Leptobryum will be added to this family soon. -RHZ.
Dale H. Vitt
Plants acrocarpous, erect to ascending, simple to sparsely branched. Leaves ovate-lanceolate to ligulate; costa strong, single. Seta slender and usually very long, to 10 cm. Capsule clavate; with an erect, long, well-defined neck abruptly merging to a wider, smooth, horizontal, spore-bearing portion. Peristome diplolepidous, exostome of 16, short, obtuse teeth (but elongate in Paludella), endostome of 16 longer segments, cilia short or absent. Calyptra cucullate.
Genera 4 (3 in
the flora): widespread in northern North America, Europe, and Asia, disjunct
in South America, Africa,
The family is characterized by capsules with long necks that abruptly expand into the spore sac. These acrocarpic plants have no differentiated alar cells, generally occur on peaty substrates, have long setae, and reduced diplolepideous peristomes.
REFERENCES Crum, H. and L. E. Anderson. Meesiaceae. Mosses of
1. Leaves squarrose-recurved (moist or dry); leaf cells bulging-conic . . . 3. Paludella
1. Leaves erect, flexuose to wide-spreading); leaf cells smooth.
2. Leaf cells lax, thin-walled; oblong-rhombic to oblong-hexagonal . . . 1. Amblyodon
2. Leaf cells firm-walled; irregularly isodiametric to shortly rhombic . . . 2. Meesia
1. AMBLYODON Palisot de Beauvois. Magasin Encyclopédique 5: 323. 1804, name conserved * [Greek ambly, blunt, obtuse, and odon, tooth, alluding to the blunt peristome teeth]
Leaves loosely erect to erect-spreading, not 3-ranked; margins plane; cells distally lax, pellucid, thin-walled, oblong-rhombic to oblong-hexagonal, smooth, basal cells similar to the distal.
North America, Europe,
Amblyodon is characteristically found in calcareous fens and meadows.
1. Amblyodon dealbatus (Hedwig) Bruch & Schimper in P. Bruch, W. P. Schimper and W. Gümbel, Bryol. Eur. 4: 7. (fasc. 10. Monogr. 5) 1841
Meesia dealbata Hedwig., Spec. Musc. Frond., 174. 1801
Plants to 1(--2.5) cm. Stem leaves loosely erect to flexuose when dry, erect-spreading when moist; narrowly oblong, 2--4 mm, not decurrent, sharply acuminate-acute; margins plane, entire or subentire; costa wide, ending well before apex. Sexual condition usually autoicous. Seta 1.2--4 cm. Capsule 2--3 mm. Spores 30--40 µm.
Sporadically on rotting wood and organic soil in rich fens scattered across the boreal zone; Alta., B.C., Man., Nfld., N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Colo., Mich., Minn., Mont., Wis., Wyo.; North America; Europe; Asia.
The lax, thin-walled leaf cells distinguish Amblyodon dealbatus from species of Meesia.
2. MEESIA Hedwig, Spec. Musc. Frond., 173. 1801, conserved name * [For David Meese, 1723--1770, Dutch gardener]
Leaves erect to wide-spreading, some species 3-ranked; margins plane to reflexed below to recurved throughout; cells distally firm-walled, irregularly isodiametric to short-rhombic, smooth, longer basally.
Species 12 (3
in the flora): North, Central, and South America; Europe; Asia; Africa;
Meesia occurs on calcareous soil banks and in rich fens in boreal, alpine, and Arctic situations.
1. Leaves ligulate, not 3-ranked, erect when moist, leaf margins revolute basally . . . 1. Meesia uliginosa
1. Leaves ovate-lanceolate to lanceolate, 3-ranked, spreading when moist, leaf margins plane basally . . . .
2. Leaves serrulate distally; dioicous . . . 2. Messia triquetra
2. Leaves entire; synoicous . . . 3. Meesia longiseta
1. Meesia longiseta Hedwig, Spec. Musc. Frond. 173. 1801
Plants 0.4--0.8 cm. Stem leaves spreading and somewhat twisted when dry, irregularly spreading and indistinctly 3-ranked when moist; ovate-lanceolate to lanceolate, 2--3.5 mm, decurrent, acute to narrowly obtuse; margins reflexed in basal portion of leaf, entire; costa narrow, ending in or just before apex. Sexual condition synoicous. Seta 5--11 cm. Capsule 3.5--4.5 mm. Spores 36--44 µm.
Calcareous soil banks and rich fens in boreal, alpine, and Arctic situations; Alta., B.C., Man., Nunavut, N.W.T., Ont., Yukon; Alaska, Calif., Conn., Idaho, Ind., N.H., N.Y.; boreal and Arctic Eurasia.
Meesia longiseta is distinguished from M. triquetra by the entire leaf margins, synoicous sexual condition, and leaves generally more slender. This species occurs in habitats similar to those of M. triquetra.
2. Meesia triquetra (Jolyclerc) Ångström, Nova Acta Reginae Soc. Sci. Upsal. 12: 357. 1844
Mnium triquetrum Jolyclerc, Systême Sexuel des Végétaux, 749. 1803
Plants 0.1--1.2 cm. Stem leaves contorted when dry, wide-spreading and distinctly 3-ranked when moist; ovate-lanceolate, 1.5--4 mm, decurrent, acute; margins reflexed below, serrulate; costa narrow, ending in or just below apex. Sexual condition dioicous. Seta 3--10 cm. Capsule 3--4.5 mm. Spores 33--38 µm.
Rich fens in arctic and boreal areas and disjunct in a few locations farther south; Greenland; Alta., B.C., Man., Nfld. and Labr (Nfld.), N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Calif., Mich., Minn., Mont., Nebr., N.J., N.Y., Oreg., S.Dak., Vt.; boreal and Arctic Eurasia.
Meesia triquetra is a species frequent where appropriate habitat is available. It is usually easily distinguished by three-ranked, widely spreading leaves that have serrulate margins. The sexual condition is dioicous. Meesia uliginosa has ligulate leaves with clearly revolute margins. The quadrate distal leaf cells differentiate species of Meesia from Amblyodon dealbatus, which has elongate, pellucid leaf cells.
3. Meesia uliginosa Hedwig, Spec. Musc. Frond., 173. 1801
Plants 0.1--0.3 cm. Stem leaves erect to flexuose when dry, erect when moist; ligulate to narrowly lanceolate, 2--4 mm, not decurrent, obtuse to rounded; margins revolute to near apex, entire; costa wide, ending just before apex. Sexual condition usually dioicous. Seta 1.5--5 cm; capsule 1.5--4 mm. Spores 40--51 µm.
moist calcareous soil banks, and soil covered rock crevices; Greenland; Alta.,
The ligulate leaves and strongly revolute leaf margins are distinguishing features of Meesia uliginosa. The leaves are erect when moist or dry and the costa is quite strong. The seta are generally much shorter than those of either M. triquetra or M. longiseta.
3. PALUDELLA Bridel, Muscol. Recent. Suppl. 3: 72. 1817 * [Greek palus, marsh, alluding to marshy habitat]
Leaves squarrose-recurved, not 3 ranked; margins broadly reflexed near middle; distal leaf cells thick-walled, rounded-hexagonal, bulging-conic on both surfaces, longer basally.
Species 1; circumboreal, North America;
Paludella is a monotypic genus occurring in calcareous fens.
1. Paludella squarrosa (Hedwig) Bridel, Muscol. Recent. Suppl. 3: 72. 1817
Bryum squarrosum Hedwig, Sp. Musc. Frond., 186. 1801.
Plants about 3--7 cm. Stem leaves squarrose-recurved, stiff when moist or dry, obovate to elliptic, 1.5--2 mm, acute to shortly acuminate; margins broadly reflexed, serrulate distally; costa narrow, ending below apex. Sexual condition dioicous. Seta 2.5--4.5 cm. Capsule 2--3 mm. Spores 15--22 µm.
fens; Greenland; Alta., B.C.,
Paludella squarrosa is one of the most spectacular moss species in the flora. The squarrose-recurved leaves (more squarrose than in any other species, even Rhytidiadelphus squarrosus) combined with the calcareous wet fen habitat are all that is needed for identification.