E-Flora BC: Electronic Atlas of the Flora of British Columbia

Species description:
Genus name derived from the sporangium shape (like an urn); the species name, from Lapland, the original place from which the moss was named.

Reproduction:
Sporophytes relatively frequent, maturing in spring to summer; sporangia light brown, grooved when mature and nearly im­mersed among leaves.

Distinguishing characteristics:
When with sporangia, the grooved urns and lack of peristome teeth distinguish this moss from most others in rock crevices.

Habit:
Forming tight, dark green to light green tufts and cushions; leaves contorted when dry, wide-spreading when moist.

Similar Species:
Amphidium mougeotii cannot be easily distinguished, even on microscopic characters, although the leaves tend to be much narrower and less contorted when dry and blunt marginal teeth are of­ten present (absent in A. lapponicum); Zygodon viridissimus is somewhat similar and is usually without sporangia (and produces numerous axil­lary gemmae, absent in Amphidium), the leaves are usually sharp toothed near the apex; Anoectangium aestivum is superficially similar but the tufts are usually bright yellow-green (dark green in Amphidium) and the leaves are not contorted when dry; Gymnostomum and Hymenostylium are found on calcareous rock and the sporophytes are not grooved and extend on a long seta. Grimmia torquata usually forms rounded hard tufts directly on the rock surface and the leaves, when dry, are cork­screw twisted around the stem; in Amphidium lapponicum the leaves are contorted, but not spirally twisted around the stem and tufts are in rock crevices. Tiny hyaline tips of the leaves in Grimmia torquata and absent in Amphidium provide another useful character visible at lOX magnification.