Click on the image below to view an
expanded illustration for this species.
Genus name describing the obliquely oriented sporangia of many species. Species name referring to the teeth at the leaf apex.
Sporophytes occasional, light brown when ripe; maturing in spring.
The flattened, glossy, pale to dark green plants, the leaves that lack an obvious midrib (the double midrib is usually obscure), the abruptly pointed leaf apex and the elongate, slightly curved sporangium are useful distinguishing features.
Forming glossy, flattened, pale green to dark green, creeping shoots in which leaves are slightly or not undulate.
Plagiothecium laetum closely resembles P. denticulatum but is usually much smaller and found most frequently on shaded, rotten logs; P. denticulatum is frequently on humid rock surfaces. Microscopic details, especially the cells of the leaf base as they extend down the stem, are the most useful identification features: in P. denticulatum these cells are thin-walled and swollen; in P. laetum they are not swollen. P. cavifolium usually has somewhat turgid, instead of flattened, shoots and is mainly terrestrial or in cliff crevices. Porotrichum bigelovii also has flattened leafy shoots, like Plagiothecium denticulatum, and occurs on damp cliffs, but the leaves have a strong midrib, tend to diverge almost at right angles to the stem (those of the Plagiothecium diverge at an acute angle toward the shoot apex), and the shoots are wiry, compared to the soft shoots of Plagiothecium. Hookeria lucens and H. acutifolia show the outlines of the leaf cells clearly under lOX magnification and lack the decurrent bases present in Plagiothecium denticulatum. Rhynchostegium serrulatum, extremely rare in British Columbia, has a midrib and the leaves have toothed margins. See also notes under Neckera, Metaneckera and Plagiothecium undulatum.