3. Simple Simon?
Moss grows on thin stems that have no vascular properties, which makes sense as they have no roots either, as there is no need for a system built to carry water and nutrients from the soil to the above ground plant. The stem puts out leaves that are (usually) one cell thick. It also produces thin filaments that produce spores. (I am trying to stay away from complicated lingo such as gametophyte, the “green” stage of the plant and sporophyte, the reproductive stage of the plant, not to mention rhizoids – the structures, not roots – that allow moss to anchor itself to some convenient surface).