Hart's-tongue Thyme-moss - Plagiomnium undulatum

    Alt Name
    Mnium undulatum
    Description

    All Plagiomnium species have greenish stems without red or brown pigments. The leaves are bordered by long, narrow cells, and usually toothed (although the teeth may be absent on some shoots). When well-grown, this is a striking and unmistakable moss with tongue-shaped, undulate leaves 2 to 5 mm long. Its stems may be tall (up to 15 cm long) and branched, like a tiny tree. The leaf base runs down onto the stem. However, stunted forms are much less distinctive, with shorter and scarcely undulate leaves. In spring, shoots with immature, pointed leaves, can also be confused with other species. Difficult forms can be identified by the leaf cells, which are much smaller than in other Plagiomnium species, and hardly longer than wide. With a little experience, or if other species are present for comparison, this can be appreciated in the field with a ×20 hand lens. Capsules are infrequent, but occasionally produced in abundance, with several growing from one shoot. They are 5 mm long, and borne on a seta 3 cm tall.

    Identification difficulty
    Habitat

     Common on base-rich or neutral soil in woodland, grassland and on rocky banks, occasionally in flushes.

    When to see it

    All year round.

    UK Status

    Widespread and frequent in Britain.

    VC55 Status

    Fairly frequent in Leicestershire and Rutland.

    Leicestershire & Rutland Map

    UK Map