Identification notes
Well-developed plants normally stand out. They have a very characteristic yellowish colour and form low-growing, spreading mats with numerous short, stubby branches on hard acidic substrates. Shade forms are greener. A quick check with a hand lens confirms that all leaves lack hair-points and capsules are frequently present.
R. fasciculare likes very open, xeric situations and is a common member of a characteristic upland boulder- or wall-top community which may include R. heterostichum s.str., R. obtusum, R. affine and Grimmia trichophylla.
When plants are wet, the narrow leaves often cling together like fur. For confirmation, examine the upper leaf cells under high power to see how the narrowly elongate cells appear to run into one another because they have thin transverse cell walls.
Read the Field Guide account