Lichen: Rhizocarpon lavatum
Pronunciation: Rhizocarpum levatum
Conservation Evaluation: Least Concern
Body Type: Crustose
Description: This crustose lichen forms large (up to 10cm) pale grey patches on rocks near streams. Sometimes the patches are tinted with brown and if in the shade (or very wet) they take on a greenish colour. The edge or prothallus is ill-defined. The apothecia are rarely larger than 1.5mm and have a distinctive appearance in that they are rather flat, ranging from very slightly concave to very slightly convex. The wide rims are flat (co-planar) with the disc but are paler and the discs often have a small mound of sterile tissue (umbo) at their centres.
Chemical Tests: All negative. No lichen products detected.
Nature Notes: Found in upland regions on both silica rich and calcareous rocks at the edge of small streams or around lakes. It likes to be washed by water regularly and is very common in Ireland.
Photographed: Co. Galway near Killary Harbour.
Similar species: other Rhizocarpons.
Vice county distribution map: See map.
Link: Map this species on the Lichen Survey
Other species recorded in Ireland:
- Rhizocarpon advenulum (Leight.) Hafellner & Poelt *
- Rhizocarpon badioatrum (Flörke ex Spreng.) Th.Fr.
- Rhizocarpon distinctum Th.Fr.
- Rhizocarpon furfurosum H.Magn. & Poelt
- Rhizocarpon geminatum Körb.
- Rhizocarpon geographicum (L.) DC. 
- Rhizocarpon hochstetteri (Körb.) Vain.
- Rhizocarpon lecanorinum Anders
- Rhizocarpon oederi (Weber) Körb.
- Rhizocarpon petraeum (Wulfen) A.Massal.
- Rhizocarpon polycarpon (Hepp) Th.Fr.
- Rhizocarpon reductum Th.Fr.
- Rhizocarpon richardii (Nyl.) Zahlbr.
- Rhizocarpon subgeminatum Eitner
- Rhizocarpon umbilicatum (Ramond) Flagey
- Rhizocarpon viridiatrum (Wulfen) Körb.
Text and images © Paul Whelan, 2010.