Description:
The common liverwort is a thallose liverwort. The thallus is thin green sheet that you are looking at. The most common liverwort found in nurseries and glasshouses is Lunularia cruciata. The complex thallose genera Lunularia and Marchantia are probably the most widely noticed liverworts.

Flowering:
In the photo the semi-circular cups are gemma cups, each containing what look like tiny green "balls", about half a millimetre in diameter. Each of those is a gemma, an aggregation of cells that can be washed or splashed out of a gemma cup by flowing water or falling raindrops. A gemma that lands in a suitable place will grow into a new liverwort plant. There are also abundant, pin-prick air pores covering the thallus.

Threats:
This liverwort does reasonably well.

Management:
Grows in damp places.