Snow-in-Summer is surely a very descriptive name for this low growing, white flowered and silvery foliaged plant. There are myriads of small white flowers produced in June from a dense mat of growth. Cerastium tomentosum is the common species and grows about 6 inches high. C. Biebersteinii is very similar but grows a little taller and has larger flowers. C. arvense is a green leaved species and stands the hot Summers better than the other two.
Field mouse-ear was first found in Finland in the mid-19th century. This most vigorous species seems to have become common in the 1930s, but perhaps that’s rather when botanists began to view these new additions to Finland’s flora as being worthy of inspection. Field mouse-ear’s settling in to grow wild in Finland is connected with the replacement of natural meadows with seeded lawns and meadows: the species arrived with foreign grass seed, along with many other species. The way that field mouse-ear spreads so efficiently through its runners means that a single plant can create a wide stand. It can be deduced, however, from the way that it arrived, that it can also spread by seed. Its beautiful flowering time begins around midsummer and it can bloom until the beginning of the early autumn.
Field mouse-ear has not yet reached the limit of its habitat; new stands are still appearing. Its most common habitat are on culturally-influenced land, roadsides and sloping meadows. Common mouse-ear (C. fontanum), which thrives in dry meadows, is the most common species of the genus in Finland, but it has clearly smaller flowers than field mouse-ear and its petals are around the same length as its sepals. Field mouse-ear has not yet spread to Lapland. Alpine mouse-ear (C. alpinum) which grows there has large flowers and slightly broader leaves than field mouse-ear, but they otherwise look alike. Alpine mouse-ear quite often moves from its wild habitat to waste ground and banks.