This is one of the more distinctive jelly lichens. It forms compact cushion-like colonies that swell up remarkably when wet to 1.5cm in diam and up to 1cm thick with erect, wrinkled lobes. As with all Collema species it lacks a distinct cortex. Apothecia are infrequently produced in Wales but where they do occur have a noticeably thick and wrinkled margin. The spores are unmistakable, being worm-like and with a spiral twist inside the ascus. They are made up of 9 to 16 cells and are between 50 and 95 microns in length.
|Collema fasciculare - wet state (Photo: R.G. Woods).||Collema fasciculare - dry state (Photo: R.G. Woods)|
In Wales it has been recorded on the basic bark of mature elm and ash. Elsewhere in Britain it is recorded from hazel and occasionally amongst mosses on basic rock outcrops. It appears to favour moist, shady sites.
Pentecost (1987) notes a specimen collected by PW James c.1970 on ash bark by a stream in SH52 held in the Natural History Museum. Ray Woods found it on an elm at Llysdinam, Brecknock SO05 and on elm below Aberedw Rocks, Radnorshire SO04. By the mid 1980’s both trees had been lost to Dutch elm disease. The BLS database has a record from SH61, the details of which have yet to be traced.