Dr M loves Grimmiales, well it’s such a wonderful bryological name! And a great big order of epiphytic acrocarpous mosses of walls and rocks and boulders and related habitats.
The leaves are oval-lanceolate, dull green, sometimes with characteristic white hair points (e.g. Grimmia, Schistidium, Racomitrium etc).
When present the capsule is on straight or curving seta, the calyptra is mitre-shaped and beaked.
Around 600 species world-wide.
Grimmia pulvinata - a really common acrocarpous moss of lowland walls, characteristic and easy to find. Grimmia pulvinata forms compact, almost hemispherical cushions with the long hair-points lending a whitish-grey colour to the plant, especially when dry. The long, much curved seta (capsule stalk) distinguishes this plant from other species with hair-points (e.g. Schistidium (Grimmiales, see below) and Tortula and Syntrichia (Pottiales)). In the early stages the seta effectively buries the ovoid capsule and its beaked lid amongst the leaves, though the seta straightens out with age.
Schistidium crassipilum – another common acrocarp of lowland wall tops and boulders. This species grows as rounded cushions or extensive flat patches with a whitish, hoary appearance due to the hair-points, conspicuous especially when dry. The capsules are largely hidden by sheathing leaves, but the red lid with short beak and the red, wide-spreading peristome teeth (when ripe) are all characteristic features.
Dr M challenges you to check out the mosses on the next wall-top you pass, look with your hand lens, Grimmiales (and Pottiales too) will be there for sure!