I have been watching this liverwort grow and spread in a plant pot on my decking with some interest. It also goes by the names of Mountain Liverwort and Star-headed Liverwort, and it is one of the largest thallose liverworts. It spreads and branches across substrates, and in younger plants it is pale or yellowish-green, becoming brown or purplish as it ages. Note how the plant is covered in conspicuous holes or air pores, and cup-shaped gemma receptacles. Male plants have stalked, flat-topped, disc-like receptacles with rounded lobes, whilst female receptacles are similar, but with lobes which are finger-like.
It can be seen all year round, with the reproductive structures appearing in June. This species is almost always found in man-made habitats, especially gardens, greenhouses, and garden nurseries where it can become a troublesome weed growing in plant pots. It is also found on waste ground, footpaths and brickwork, and also by streams and rivers. It is abundant and widespread throughout.
Photographs of Common Liverwort (Marchantia polymorpha subsp ruderalis), taken September 2016, rear garden, Staffordshire. © Pete Hillman 2016. Camera used Nikon D7200, with Sigma 105mm macro lens.