Lichen: Collema tenax
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Name: Collema tenax (Sw.) Ach. (1810) var. tenax
Collema tenax - when wet
Apothecia of Collema tenax
Description: Thallus is black when dry; when wet it swells and takes on a brown and dark olive green colour. The edges are characteristically ragged and sometimes ascending. Frequently forms neat radiating rosettes. The centre of the thallus is regularly folded over itself and increases the height of the centre. The wide lobes (< 1cm wide) are isidiate and granular. Pycnidia are common. Apothecia reach a diameter of 3cm are common, and have a distinct red brown colour. The discs are smooth and the rims smooth or sometimes warted. Spores are 15-25 x 6-10 in size μm and 3 septate to muriform and a high magnification required view. Asci 4-8 spored.
Spot Tests: None for Collema.
Nature Notes: Found on basic or calcium rich soils and mortar. Frequently associated with towns and individual dwellings. Despite being a common Collema it is also very variable and has three different forms. (i) var. ceranoides has many thin ascending lobes and rarely displays apothecia, (ii) var. corallinum has apothecia, is more crustose than the others. Unrecorded to date in Ireland. (iv) var. vulgare has short convex lobes and many apothecia
Vice county distribution map: See map.
Link: Map this species on Lichen Survey at www.biology.ie
Other species recorded in Ireland:
- Collema auriforme (With.) Coppins & J.R.Laundon
- Collema bachmanianum (Fink) Degel.
- Collema confertum Arnold
- Collema crispum (Huds.) F.H.Wigg.
- Collema crispum var. crispum
- Collema cristatum (L.) F.H.Wigg.
- Collema cristatum var. marginale (Huds.) Degel.
- Collema dichotomum (With.) Coppins & J.R.Laundon
- Collema fasciculare (L.) F.H.Wigg.
- Collema flaccidum (Ach.) Ach.
- Collema fragile Taylor
- Collema fragrans (Sm.) Ach.
- Collema furfuraceum (Arnold) Du Rietz
- Collema fuscovirens (With.) J.R.Laundon
- Collema glebulentum (Nyl. ex Cromb.) Degel.
- Collema limosum (Ach.) Ach.
- Collema multipartitum Sm.
- Collema nigrescens (Huds.) DC. [14]
- Collema polycarpon Hoffm.
- Collema subflaccidum Degel.
- Collema subnigrescens Degel.
- Collema tenax var. ceranoides (Borrer) Degel.
Text and images © Paul Whelan, 2009.