The Lichens of Ireland: An Illustrated Introduction to Over 250 Species

161 Pages·2011·284.452 MB·English

by  Paul Whelan

Lichens of Ireland
An illustrated introduction
to over 250 species
Paul Whelan
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Lichens of Ireland
An illustrated introduction
to over 250 species

Paul Whelan has a degree in Biology from
University College Dublin and studied
Computer Science and Art History at Trinity
College Dublin. He published several books on
Computer Aided Design in the 1990s before
returning to his earlier interest in natural history
and focusing on Ireland’s lichen flora. In 2008
he became involved in the LichenIreland project
and developed an independent website (www.
lichens.ie), which susbequently won an Irish
Internet Association Net Visionary Award. In
2010 he developed www.ispynature.com for
primary school children. Paul lives in east Cork.
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For Anna, Aine, Molly and Pip.
Ernst Haeckel (1834–1919), lichens from Kunstformen der Natur (1904).
[Cladia retipora, Cladonia perfoliata, Cladonia cervicornis ssp. verticillata, Cladonia squamosa,
Cladonia fimbriata, Cladonia cornucopiae, Lobaria pulmonaria, Physcia aipolia, Melanohalea olivacea,
Flavoparmelia caperata, Anaptychia crinalis]
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Contents
Acknowledgements iv
Introduction v
Part One – Biology and Ecology
What are lichens? 2
Defining a lichen – A little more detail – Damsel–tyrant duality
Naming lichens – Mycobionts: fungi – Photobionts: algae and cyanobacteria
Morphs – Thallus anatomy
Growth forms and colours 7
Growth forms – Crustose lichens – Foliose lichens – Fruticose lichens
Squamulose lichens – Lichen colours
Lichen sexual reproduction 12
Sexual reproduction in ascomycete lichens:
Life cycle of ascomycete lichens – Apothecia – Structure of an apothecium
Apothecial variations – Perithecia – Spore size and the micron
Basidiomycete lichens
Spore dispersal
Asexual reproduction (vegetative) 17
Fragmentation – Soredia (and soralia) – Isidia – Schizidia – Pycnidia – Blastidia
Non-reproductive bits
A practical approach 22
A guide to basic equipment – Setting up your own herbarium
Vice-county maps – Lichen substances and spot tests
Spot tests and how to apply them – Ultraviolet light (UV) – Microscopes
How to section an apothecium – Spore septa and spore size
Ecology of lichens 26
Ireland’s geology – Where are these rocks? – Climate and substrates
Oceanic climate – Lichen substrates – Saxicolous lichens – Corticolous lichens
Bryophytes and dead vegetation
Lichen habitat types in Ireland
Lichens and pollution – Importance of lichens in an ecosystem
Some conservation pointers
Lichen communities and habitats:
Lobarion community – Graphidion community – Parmelion community
The Burren Limestone – Atlantic Woodlands, Killarney – Atlantic hazel woods
Rocky seashores
Part Two – Alphabetic Photographic Guide to Selected Lichens
Species descriptions 42
References 152
Internet Resources 153
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Acknowledgements
In particular I would like to thank John Douglass, lichenologist, for many enjoyable and informative
field trips throughout Ireland. Thank you also to Howard Fox, lichenologist with the National Botanic
Gardens, Glasnevin, Dublin, for his encouragement, and to the LichenIreland team for involving me
in field work. LichenIreland is supported by National Parks and Wildlife Service; National Botanic
Gardens, Glasnevin; Environment and Heritage Service and the Ulster Museum, National Museums
Northern Ireland.
I would like to express my thanks to Alan Orange, the National Museum of Wales, for use of
his wonderful ink drawings which help to elucidate much of the lichen terminology, and to both
the British Lichen Society and LichenIreland for access to their records of Ireland’s lichens at 10km
resolution. Special thanks must be given to the fieldworkers who walked the length and breadth of
Ireland over many years amassing more than 130,000 records of our rich lichen biodiversity. These
lichenologists include Andy Acton, Brian Coppins, Sandy Coppins, Simon Davey, John Douglass,
Howard Fox, Vince Giavarini, Joe Hope, Alan Orange, Ivan Pedley, David Richardson, Neil
Sanderson, Jenny Seawright, Mike Simms, Robert Thompson and Stephen Ward.
Also, thank you to Gill Weyman of the Irish Wildlife Trust, Anna O’Connor and Paula
Meenehan, for reading the text and making suggestions and also to Jenny Seawright for helping me
locate some species to photograph for the book. And thanks to Nico Nieuwstraten, who wrote a
wonderful Photoshop script file to generate the vice-county maps from the vice-county data.
Finally, I would like to express my gratitude to the Heritage Council of Ireland for financial
support under the 2011 Heritage  Education,  Community  and  Outreach scheme, without whom
this book would not have been published.
Paul Whelan
October 2011
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Introduction
Currently, Ireland is home to almost 1,200 recorded lichens and 205 lichenicolous and non-
lichenized fungi. Considering that the whole of North America has approximately 3,600 recorded
species, Ireland’s lichen biodiversity has a staggering richness for a country of its size and latitude.
This hidden richness of our natural world was relatively neglected until recently, when the
LichenIreland Project (2005–2010) began to uncover the extent of the biodiversity, particularly of
our Atlantic woodlands and hyper-oceanic hazel woods.
This book is the result of my involvement in the LichenIreland project. It introduces beginners,
armed with a simple hand lens, to the delightful Lilliputian world of lichens. There could be much
debate as to which species should be included in a book of this nature and size. Many will feel that
species ‘X’ should have been included. However, a selection had to be made and included are some
notable species that thrive in our oceanic climate, and some dots-and-squiggles lichens that are
rather difficult to identify. All will contribute in some way to challenge beginners, and prepare them
for more advanced texts such as Frank Dobson’s Lichens (6th edition) or The Lichens of Great Britain
and Ireland, 2009 edition (British Lichen Society).
The book lacks a key. For this I make no apology as a key would take the text beyond its current
scope, and possibly lose the readership for which it is intended. The book is necessarily brief and
sometimes simplified, but will hopefully turn the minds of Ireland’s new generation of young
naturalists to the world of lichenology. A downloadable glossary (pdf) to the book is currently
available at www.lichens.ie.
The lichens are listed alphabetically. This method was chosen after consideration of other possible
arrangements. Presentation by body form was rejected because that classification system quickly
breaks down (for example Cladonia lichens belong to both squamulose and fruticose forms) and
classification by habitat breaks down because many species straddle more than one habitat. Similarly,
classification by substrate breaks down although it was a system I gave a lot of consideration to.
Alphabetic arrangement provides more immediate rewards because the beginner will quickly learn
to recognise the genera and can flick to the relevant section efficiently.
All the photographs in the text were taken by the author over a three-year period of lichen hunting
around Ireland. The magnified insets on many images act to either show more detail or to concentrate
the eye on where to look for characteristic features (not necessarily magnified). With just a hand lens
and a willingness to understand lichens, you will open up a miniature world of immense beauty. It
is almost inevitable that a beginner using a hand lens for the first time will consider him or herself
in the shoes of Alice in Wonderland.
Some of the earliest Irish lichen records were made c. 1696 by William Sherard and Caleb Threlkeld
(1676–1728). In the twentieth century Matilda Knowles made significant contributions with her
work on seashore zonation and her 1929 publication History of Irish Lichens (available on www.
lichens.ie). Other twentieth century contributions were made by Lilian Porter, Robert Lloyd
Praeger, Annie Lorrain Smith, John Adams and more recently Howard Fox. The LichenIreland
project of 2005–2010 made a major contribution to documenting Irish lichen flora. At the time of
writing a Lichen Red Data list is imminent. Nomenclature in this text is mainly according to Smith
et al. (2009) and Hawksworth (2003).
1
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What are lichens?
Lichens contribute to the visual ‘background noise’ of our environment, providing colour and
texture to woodlands, parks, buildings, monuments and graveyards. They add the ‘old’ to old walls,
gateposts and monuments, their aesthetic value only missed when they are absent.
Lichens have been used as medicines, poisons and dyes and have contributed to making many a
child’s doll in the form of hair or bulking out material for arms and legs. Even today they are used in
the manufacture of perfume, acting as a fixative to ensure the slow release of scent. Evernia prunastri
has been used to give some perfumes a
moss-like scent. Cladonia pyxidata was
once thought to cure whooping cough.
Dyes can be extracted from lichens
and used to colour wool. Extraction
sometimes involved boiling or soaking
them in urine. During the nineteenth
century lichens became economically
valuable, often demanding prices in
excess of the cost of rare spices. A large
cottage industry developed around
lichen dyes.
Lichens act as a source of nitrogen
for many plants and are frequently the
first living forms to inhabit bare rock.
Birds use them as nesting material
and they are an essential component
in food chains, being eaten by snails,
slugs, insects and higher animals such
as deer. Lichens act as biomonitors,
Crustose lichens add texture and colour to headstones in a west-
some absorbing heavy metals from their
of-Ireland graveyard. They enhance the aesthetic quality of many
environment and responding to both
buildings and monuments.
air and water quality.
Defining a lichen
Lichens (phonetic pronunciation ‘like en’ or ‘litch en’, both acceptable) are fungi that live with
a photosynthesizing partner, usually an alga or cyanobacteria. It is a clever arrangement because
many fungi are saprophytes (they feed on dead organic matter such as dead plants or animals) and
the algae and cyanobacteria are autotrophs, able to make their own food from sunlight, water and
carbon dioxide (photosynthesis). With such a dual food source, they are unlikely to starve.
A little more detail
A standard textbook definition describes lichens as two and sometimes three organisms living
together in symbiosis. This is essentially true. The three organisms in question are a fungus (related
to bread mould, although a few are related to mushrooms), algae (related to seaweed or the
green slime on ponds) and in some cases photosynthesizing bacteria belonging to a group called
cyanobacteria. The relationship is stable and they form a distinct shape and structure (both used as
identification aids) and generally live a long time. Some lichens have been estimated to be 4,500
years old. Lichen-type symbiosis has been positively identified in fossil records as old as 410 million
years (Rhynie chert in Scotland). Recent studies have pushed this back to 600 million years.
2 what are lichens?
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In 1982 the International Association of Lichenology issued the following definition of a
lichen: an ‘association of a fungus and a photosynthetic symbiont resulting in a stable thallus of
specific structure’.
In summary, a lichen is not a single organism, but an assemblage of two or three different
species working together for survival. The fungal part is termed the mycobiont and the photosynthetic
partner is the photobiont.
Damsel–tyrant duality
The dual nature of lichens was first recognized in 1869 by a German
biologist, Simon Schwendener. There was great resistance to this idea at
the time. He wrote: ‘lichens are ... colonies ... of individuals, of which
one alone plays the master, while the rest, forever imprisoned, prepare
the nutrients for themselves and their master. This fungus is a fungus
of the class Ascomycetes, a parasite which is accustomed to live upon
others’ work. Its slaves are green algae, which it has sought out ... and
compelled into its service.’ A further description around the same time,
by Rev. James Crombie, a Scotsman, described the dual relationship as Simon Schwendener (1829–
‘the unnatural union between a captive algal damsel and tyrant fungal 1919) who first postulated
master’. Regardless of which of these descriptions you favour, it was the dual nature of lichens.
determined that the fungal partner was the dominant one. Perhaps a This idea was rejected by
more concise definition of a lichen is ‘a fungus that associates with a many scientists of the time.
photobiont’. A fungus makes up the bulk of the lichen body, occupying 80% or more of the thallus;
frequently the algal part is as low as 5%. Whether the fungus enslaves the alga or cooperation is
mutual is a matter of conjecture. Both partners seem at ease with one another, although the alga has
had to give up its own sex life. Only the ‘tyrant’ fungus is the sexually active partner.
Simon Schwendener also suggested that lichens should be classified with fungi, but this was
rejected by the scientific community. Since the 1950s lichens are accepted as lichenized fungi and
have been accepted into the Kingdom Fungi. Despite this, the study of lichens has been considered
a separate study (lichenology) from the study of fungi (mycology).
Naming lichens
Carl von Linné (Linnaeus) introduced a binomial system for
naming plants and animals in the eighteenth century. Names such as
Ochrolechia parella or Homo sapiens are binomial. Latin was then in
use as the universal scientific language. Binomial names are derived
from Latin or Greek words and written in italics when printed and
underlined when handwritten. The first part of the name is the genus or
group to which the organism belongs and the second part of the name
is the species (parella or sapiens in the above examples) and is written
in lowercase letters.
Now, while Linnaeus made major progress with naming just about
every known plant and animal at the time, lichens confounded him, Carl von Linné (1707–1793)
although he did manage to describe 109 different species. Overall, he described 109 lichens and
referred to them as ‘nature’s
had little time for lichens and referred to them using the Latin phrase
paupers’.
rustici pauperrimi (nature’s paupers).
As a lichen is an assemblage of two or three distinct species, each with its own binomial name,
how do we name it? The name of a lichen is the name of the fungal partner. Consequentially, a name
such as Ochrolechia parella refers to the fungus that makes up the lichen; the photobiont does not
usually contribute to the lichen’s name.
naming lichens 3
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Mycobionts – fungi
Th e fungal partner in a lichen is termed
the mycobiont. Fungi are a large and
diverse group of organisms, comprising
at least 70,000 species worldwide.
Some fungal experts say the number is
more likely to be 1.4 million species.
Fungi are the primary ‘decomposers’
or saprophytes, in the biosphere. Many
fungi are also parasites, feeding on
living cells and tissues.
Both animals and green plants are
constructed of individual block-shaped
cells. Fungi, on the other hand, are
composed of thread-like fi laments. Th is Photograph showing a mould growing on food (jam), illustrating
fi lamentous structure has contributed the thread-like nature of fungal cells. In many crustose-type
lichens the outer growth area or prothallus is similar.
largely to their success as a group,
allowing them to grow into crevices,
enabling access to carbohydrate and
protein molecules of their hosts.
Nearly all fungi that form lichens
in Ireland come from one group,
the Ascomycetes or ‘sac fungi’, so
called because they produce sexual
reproductive spores in sacs or asci.
Only a handful of lichens in Ireland
(less than 5%) have the mushroom-
type fungi (group Basidiomycetes) as a
mycobiont. Th ese fungi do not produce
spores in sacs, but instead on club-
shaped structures, the basidia. In this
book, the terms ‘spores’ and ‘ascospores’ A crustose lichen showing the prothallus or outer growing area.
are used interchangeably. Th e orange-red colour is a free-living Trentepohlia alga.
Photobionts – algae and cyanobacteria
Photobionts use light to make molecules of glucose. Th is process of converting electromagnetic
energy into chemical energy is termed photosynthesis. All green plants photosynthesize, as do all
algae and cyanobacteria. Many lichens contain both algal and cyanbacterial photobionts in the
same thallus; however, one is dominant and is termed the primary photobiont. Algal photobionts
contribute sugars to the fungus; cyanobacteria also provide sugars, but additionally supply nitrogen
in a form (nitrates) the fungus can use to build up its body tissue (mainly proteins).
Algae belong to the Kingdom Protista and those found in lichens belong to the genera
Trentepohlia (orange in colour) and Trebouxia (bright green in colour). Th e group Trebouxia are
unicellular and by far the most common green algae integrated into lichens, but rarely found free-
living. Trentepohlia algae, on the other hand, grow freely outside lichens as fi laments, but when
part of the lichen symbiosis they become single cells. Crustose lichens tend to have Trentepohlia
algae as their photobiont. Lichens whose only photobiont is green algae are termed chlorolichens.
A group called the ‘jelly lichens’ have a predominance of cyanobacteria (their primary photobiont)
and belong to the genera Collema and Leptogium. Nostoc cyanobacteria are found in jelly lichens.
4 mycobionts
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