Zygodon forsteri (knothole moss, Forster’s yoke-moss)

Zygodon forsteri  Knothole Moss (Forster’s Yoke-moss) is a highly specialised epiphyte occupying a very narrow ecological niche. In the northern part of its range its host (phorophyte) is almost invariably Beech (Fagus sylvatica), although plants have been found on Quercus robur (once) and Acer campestre in the British Isles and on Ulmus spp. in continental Europe.

Zygodon forsteri is listed as Vulnerable in the 1995 Red Data Book of European Bryophytes (Söderström et al., 2005). In Great Britain the species is classified as Endangered in the British Red Data Book (Church et al., 2001). It is protected under Schedule 8 of the Wildlife and Countryside Act, 1981 and has been a UK Biodiversity Action Plan (BAP) priority species since 1999 (Anon, 1999).While higher than ever before, recent survey figures undoubtedly actually mask a worrying decline.

Species detail

  • Knothole Moss (Zygodon forsteri)

    Forster's yoke-moss is a distinctive species, being the only autoicous (with male and female organs on the same plant) European species within the genus and also the only one with smooth leaf cells. find out more about ths taxonomy of this species.

  • Zygodon forsteri on knots in roots
    Distribution and ecology

    The knothole moss has a wide range but is rare within this range. Discover the areas where this moss is known from and the types of habitat it is most regularly found in. Get a more detailed account of its British distribution.

  • Knothole Moss (Zygodon forsteri)

    Zygodon forsteri plants are about 1cm tall, blackish green, forming small open cushions of a soft consistency, or loose turfs, often from persistent protonema. Find out more about the structure of this rare moss.

  • Knothole Moss (Zygodon forsteri)

    Find out the conservation status of Zygodon forsteri Europe-wide and more specifically in Great Britain. Read about the management practices in place to aid the survival of this species and potential management techniques to be used in future for the species.

  •  Zygodon forsteri Knothole Moss or Forster’s yoke-moss.

    Get reference material for Zygodon forsteri.

About the author

Fred Rumsey
Dr Fred Rumsey

Botanist - Identification and Advisory Service,  Angela Marmont Centre for UK Biodiversity.

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