Peltigera praetextata (images of British lichens)

Upper surface of fresh thallus tan to brown-grey or brownish black, minutely felted-tomentose at least at the margins but tomentum usually invisible when wet, bullately wrinkled, margins of older thalli isidiate, often also with groups of laminar isidia (but isidia may be lacking from younger lobes or those with with apothecia); lower surface white-tomentose, with unbranched rhizines.

Refs: Vitikainen (1994) 74-77 (photo); Smith et al. (2009), 671; Purvis et al. (1992), 443; Dobson (2005), 319 (photo); Dobson (2011), 320 (photo); Jahns (1983), 240-241 (photo); Nordic Lichen Flora (2007) 3: 126, 198 (photo); van Haluwyn et al. (2009), 69-9 (photos); Moberg & Holmåson (1984), 177 (photo); Holien & Tønsberg (2008), 122 (photo); Wirth (1995), 2: 680, 689 (photo); Wirth et al. (2004), 163 (photo); Brodo et al. (2001), 518-519 (photo); Hinds & Hinds (2007), 371-2 (photo); McCune & Geiser (2009), 239 & 256 (photos).

The only common British Peltigera with isidia, but compare P. collina with marginal soredia. When drying, this species can easily be overlooked as P. membranacea, but is normally distinguished by the isidiate margins of the older lobes. Widespread and locally common on mossy boulders, tree-bases and on damp, heathy banks.

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Images of British Lichens