LichenIreland
  • Collema cristatum (L.) F.H.Wigg.
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Collema cristatum
© Mike Simms
Collema cristatum
© Mike Simms
Collema cristatum
© Mike Simms
Collema cristatum
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This green-black, rosette-forming ‘jelly lichen’ disintegrates when old, leaving semi-circular ‘moons’ of thallus still attached to the rock; this can be a useful character. When dry it looks like a small, compact, crispy seaweed but is more like a slice through a cauliflower when wet, when the lobes are at their most convoluted. Occasional wart-like isidia are present. Discs are common (to 5mm diam.). It grows on hard limestones; also on mortar and tombs in old churchyards. It is common in Ireland.

Key characteristics

  • Jelly lichen, crisped when dry, wrinkled and convoluted when wet, discs common
  • Easily disintegrating when dry (centres fall out) to leave arcs of thallus.

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Collema cristatum (L.) F.H.Wigg.. [In] LichenIreland.
http://www.habitas.org.uk/lichenireland/species.asp?item=18435 Accessed on 2017-12-18.