Previous page Next page

Images of British Lichens

Placopsis gelida (L.) Linds.

Thallus a cream, markedly placodioid crust, usually with conspicuous, rounded, lobed, flesh-coloured cephalodia scattered over the surface, and with the central area pale green-grey-sorediate, the soralia excavate-eroded with a corticate rim and becoming confluent; apothecia very rare. On rocks, distribution uncertain but apparently arctic-alpine.

Refs: Moberg & Carlin (1996), Symbolae Botanicae Upsaliensis 31: 319-325 (photo); Smith et al. (2009), 711; Purvis et al. (1992), 474 (as aggregate only); Dobson (2005), 346 (as aggregate, photo seems to be P. lambii); Dobson (2011), 348 (excluding photo); Wirth, Hauck & Schulz (2013), 2: 890 (photo); Holien & Tønsberg (2008), 182 (photo); Stenroos et al. (2011), 371 (photo); Hansen & Andersen (1995), 107 (photo); Thomson (1997), 471, 472 (line illustration, evidently as aggregate).

Difficult to distinguish morphologically from the evidently more common (especially in metal-rich areas) P. lambii, but the latter has a generally more shiny thallus, yellow-grey to brown cephalodia, more clearly delimited, convex and often concentrically arranged soralia with soredia grey-green to blackish, and much more frequently produced apothecia, though separation on chemical characters may be needed. Descriptive details taken from Moberg & Carlin (1996) (see above); other and especially earlier sources unreliable.

Placopsis gelida
Placopsis gelida
Placopsis gelida
On montane rockface near Ben Lawers, Perthshire, April 2003 (taken in very poor light)

Previous page   Next page

Lichens HOME PAGE | Index of Species | Conditions of Use and e-mail contact | References | Site Home Page

© A.J. Silverside
Uploaded September 2008, last updated September 2013