Orthotrichum laevigatum

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Copyright: Flora of North America Association

Plants (0.5–) 2 (–4.3) cm, light green to olive green. Stem-leaves stiff, erect-appressed, slightly secund when dry, oblong-lanceolate, lanceolate, or ovatelanceolate, 2–4.3 mm; margins revolute from base to near apex, entire; apex obtuse, bluntly or narrowly acute, or gradually acuminate; basal laminal cells rectangular to elongate, grading to elliptic-quadrate, walls thick, nodose; distal cells 8–12 µm, 1-stratose, papillae 1–3 per cell, conic or 2-fid, low. Specialized asexual reproduction absent. Sexual condition gonioautoicous. Seta 1.5–4 mm. Capsule fully exserted, cylindric, 1.4–2.6 mm, smooth or sometimes slightly plicate distally; exothecial cells homogeneous; stomata superficial; peristome double; prostome absent or rudimentary; exostome teeth 16, erect, papillose; endostome segments 8, occasionally rudimentary, usually absent in open capsules, of 1 row of cells, smooth. Calyptra conic-oblong, smooth, sparsely hairy, hairs finely papillose. Spores 10–15 µm.

Habitat: Non-calcareous boulders in mesic, open coniferous forests, base of deciduous trees
Elevation: moderate to high elevations (500-3000 m)

Alta., B.C., Man., N.W.T., Sask., Yukon, Alaska, Ariz., Calif., Colo., Idaho, Mont., Nev., Oreg., S.Dak., Utah, Wash., Wyo., Europe, e Asia (Japan)

Discussion

Orthotrichum laevigatum is part of a complex group of intergrading taxa that generally are characterized by exserted, cylindric capsules with 16 erect or reflexed exostome teeth and a poorly developed endostome. Gametophytically, robust plants have stiff, erect leaves and large, blunt papillae. This complex is treated here as three species: O. holzingeri, a distinct, highly specialized species of seasonally wet rock with smooth exostome teeth, smooth laminal cells, smooth calyptra, and slightly ribbed capsule as distinguishing features; O. laevigatum, distinguished by smooth capsule and erect, papillose exostome teeth; and O. pylaisii, distinguished by slightly 8-ribbed capsule and reflexed-recurved exostome teeth.

Selected References

None.

Lower Taxa