Grimmia orbicularis

Description:

Moss. Grimmia orbicularis grows in dark green to greyish, hoary, usually hemispherical cushions, leaves are appressed and twisted when dry, erect when moist, broadly lanceolate, abruptly contracted into hair-point, keeled above. Hair-points are short to long, smooth to denticulate, margins are recurved in the middle of the leaf, on one or both sides. The capsules are usually present, they are exerted, bent down into the cushions by the arcuate setae, ovoid and smooth, peristome teeth are orange, broad, cribrose, irregularly cleft t apex, operculum is mammillate. G. pulvinata most resembles G. orbicularis, with which it sometimes grows, but G. orbicularis has a rounder capsule and a lid with a blunt, nipple-like tip.

Habitat:

G. orbicularis grows on limestone (particularly Carboniferous) rocks and boulders in the lowlands, often in sunny, exposed places. Less often, it grows on the mortar of old walls. Spotted on an small bridge made with mortar.