It is not actually moss. It is of the same family as carnation. Of course, any distinguishing characteristics of its family are difficult to recognize. Iris moss, Sagina subulata, has such exceptionally fine foliar texture and diminutive bloom. Its slim leaves are not much longer than a quarter of an inch. its tiny white flowers are barely wider than an eighth of an inch.
Irish moss is a luxuriantly dense and richly evergreen ground cover for confined spaces. It works well within small atriums and big pots that contain sculptural plants that lack low foliage. It is a popular accessory for Japanese maple and citrus within tubs. Since it gets no more than two inches deep, Irish moss can fill in between pavers and under benches.
However, Irish moss dislikes how pavement enhances harsh exposure. Although it does not require shade, it appreciates a bit of partial shade while the weather is warmest after noon. Also, it craves somewhat frequent watering to compensate for locally arid warmth. Scottish moss is the cultivar ‘Aurea’. It is lighter chartreuse green, but otherwise identical.