The star-headed liverwort (Marchantia polymorpha) is normally a rather bland and inconspicuous plant growing as a flat ribbon of cells on the surface of rocks and stones. However at this time of year it transforms itself as it ‘flowers’.
From above you can see the umbrellas along with the darker green flat part of the plant.
This is a common liverwort and can be found all over Britain but only becomes easily identifiable when the female reproductive parts emerge. There are three distinct sub-species: montivagans which grows in base rich springs in upland areas and on sand dunes; polymorpha which grows on natural rocks and stones and ruderalis which grows on man-made surfaces.
My photos are of ruderalis – it is growing between the paving stones in my garden.
Worth looking out for as it is rather striking.