• Collema tenax (Sw.) Ach.
Click on the thumbnails to enlarge the images
Collema tenax
© Robert Thompson
Collema tenax
© Mike Simms
Collema tenax
© Mike Simms
Collema tenax
Click on map to open large map in new window
(Map updated: 11 August 2009)

Click here to view an interactive map of the Northern Ireland dataset as currently collated by CEDaR.
The map is generated through the NBN Gateway using their Interactive Mapping Tool.


This is a dark green to black, almost rosette-forming ‘jelly lichen’ with very conspicuous swollen, squashy lobes, especially noticeable when moist. The reddish-brown discs (to 3mm diam.) are frequent. It occurs mostly on basic soils and clays and man-made substrata such as mortar. Its close relative, Collema tenax var. ceranoides, is distinguished by an abundance of narrow, thin, ascending lobes arising from spongy cushions often found embedded in paths and tracks, frequently in gardens. Both varieties are abundant in Ireland.

Key characteristics

  • Jelly-like, thick, blackish thallus frequently packed with reddish-brown fruits
  • When moist, plump, like an inflatable air bed; cracks in damp mortar especially.

Original text submitted by Simon Davey

 Simms, M. J., (2016). Collema tenax (Sw.) Ach.. [In] LichenIreland. Accessed on 2018-08-20.