“low bristle moss”
How to recognize low bristle moss: Orthotrichum pumilum occurs in small dark green tufts. It is a cushion moss with little 1-1.5 mm long capsules barely emergent above the upper leaves. This moss genus has significant differences between the capsules which require a compound microscope to sort them out. The calyptra (capsule cover while developing) is naked or sometimes with a few sparse hairs. The apiculate leaves which are erect when dry and wide spreading when wet, have large cells compared to other species in this genus (14-20 microns long); this and technical features of the sporophyte (immersed stomata; distinctively 8-ribbed capsules) distinguish this from several similar species.
Where to find low bristle moss: Orthotrichum pumilum occurs on the bark of hardwoods and masonry, commonly along roadsides in cities.