Lichen: Melanohalea exasperata
Name: Melanohalea exasperata (De Not.) Essl. O. Blanco, A. Crespo, Divakar, Essl., D. Hawksw. & Lumbsch (2004).
Pronunciation: melanohalea exasperata
Conservation Evaluation: Least Concern
Body Type: Foliose
Description: The thallus is olive green and shiny. It does not change colour when wet. The thallus ranges in size from 2 cm to 10 cm, although most specimens found in Ireland reach a maximum of 5 cm. The thallus divides into small lobes (1 mm to 5 mm wide) which expand towards the tips to end rounded. One of the most characteristic features of this lichen is the warty surface. The common name of Toad Lichen describes this warty texture and olive green colour. The warts look like tiny volcanoes under a hand lens; each has a conical shape with a ‘mouth’. The warts extend to the apothecia. Apothecia are common in this species; the disc surface is concave or flat.
The under surface is dark brown, becoming buff towards the edges. The rhizines are simple. Spores are colourless, one celled and 8 to an ascus. The papillae warts are evenly distributed around the rim of the lecanorine apothecia. Photobiont is the green algae Trebouxia.
Chemical Tests: No chemical reactions. No lichen substances.
Nature Notes: They like an acid environment and so are usually found on coniferous trees, but they will grow on birch, willow, alder and oak. They are rare on rock substrates.
Vice County distribution map of Melanohalea exasperata: See Map
Link: Map this species on the Lichen Survey
- Melanelia exasperata
Text and images © Paul Whelan, 2009.