Prof David Leslie Hawksworth CBE, mycologist and lichenologist, Research Professor since 2001 at the Universidad Complutense de Madrid (Complutense University of Madrid), President from 1986-7 of the British Lichen Society, from 1990-1 of the British Mycological Society and from 1994-7 of the International Union of Biological Sciences, and Editor from 200-8 of Mycological Research
Charles Christian Plitt (born 6 May 1869 in Baltimore, Maryland, died there 13 October 1933) was a botanist and lichenologist.
It is heteromerous, that is, it contains an upper cortex, medulla, green algal layer (occupied by Trebouxia spp.), and lower cortex.