Baden-Württemberg - Lichens of Wales

habitat (to facilitate determination), date and
collector.
Without any doubt impending in the
consequences of the precipitous increase in the
number of those interested in lichens is a further
danger to these already richly collected
organisms: is the decimation and extirpation by
lichenologists. In collecting lichens one ought to
consider that many lichens are rare and
endangered. In many cases the collection of only
five to ten specimens would have the result of
extirpation of the species in Germany. One
collection of rare species is without justification,
especially so, when the lichen already is known
and documented from the region. Occasionally
one can in a certain region collect species
endangered in other regions, where they are still
frequent, without an aggravating result being
“provided.”
A completely removed specimen growns no
longer. The decimation of a population can lead
to the endangering of the rest of the population.
A resettling of a species on a locality, on which it
was obliterated, seems in the case of rare foliose
and fruticose lichens in many ways extremely
unlikely. This is valid especially for species,
which reproduce with the help of relatively heavy
soredia and isidia.
3. Investigations and
Determinations of Lichens
3.1 Introduction
Most foliose and fruticose lichens may be
determined without more than the aid of a
handlens, a few without the aid of optical
devices. Important are e.g. form and color of the
thallus and the fruiting body, occurrence of warty
outgrowths (isidia) and “mealy” eruptions
(soralia) and other organs. For the determination
of crustose lichens the use of a microscope is as a
rule necessary. Indeed the experienced lichen
specialist can easily distinguish almost all lichens
including the crustose lichens by habitat and
ecological characteristics alone, but in
determination one can not commonly by
external characteristics alone, sufficiently
through our grammatical potentiality, be exact
enough about the fine distinctions in coloring and
structures to define them in keys. For this reason
measurable and clearly defined microscopic
characteristics must be applied, e.g. spore form
and size, structure of the fruiting body, coloring
of the fruiting body parts etc. For the
determination of such characteristics sections
through the fruiting body are often necessary.
The producing of sections is not difficult.
They are made much easier, when a binocular or
a dissecting scope is used, under which one can
work with both hands. At least in the larger
fruiting bodies, sections may be prepared without
the aid of lenses.
With one hand one holds the lichen fast, with
the other hand one draws an unused razor blade
parallel (vertical) sectioning through the fruiting
body. At best one removes to begin with a
marginal part, perhaps a fourth or a third of the
fruiting body and next cuts the thinnest possible
slice, as from a loaf of bread, in many lichens the
fruiting body is easily broken loose and then is
more difficult to manipulate. In this case one can
capture the fruiting body with a tweezers or a
preparation needle and glue it to a wooden or
paper support. The section can be accomplished
dry or (above all, in the case of hard fruits better)
with objects swollen with water. It can be very
helpful when one holds the object fast with one
finger so that the fingernail is almost at a right
angle and is used as “backdrop” for the razor
blade. The section may be lifted easily from the
object with the (under the circumstances)
moistened edge of the razor blade or with the
point of a preparation needle. It is then placed in
a small water drop on the slide and covered with
a cover glass. If the section is not thin enough,
one may squash it somewhat. For which one
places the slide with the cover glass beneath
upon a page of filterpaper and presses.
A considerable aid in determination is offered
by color reactions of the lichen thallus with
designated chemicals. Many lichens contain the
same substances, which with these substances
yield colored reaction products. The most
important reagents are calcium hydroxide
(KOH), calcium or sodium hypochlorite
(Ca(OCl)2 / NaOCl2) and para-Phenyldediamin
(H2NC6H4NH2). The procurement of reagents
becomes increasingly more difficult. Chemical
handling comes into question, under
circumstances even for apothecaries and
druggists. Druggists of commercial chains
today do not accept individual orders.
3.2 Important Diagnostic Characteristics
of Lichens
3.2.1 Color of the Thallus
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