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Multicellular spores with transversal septa only.
Muriform (wall-like) spores
: multicellular spores with both transversal and longitudinal septa.
SPOT TESTS
Many lichens contain chemical compounds, some of which have been used to make dyes, and others
as sunscreen products. These compounds are also useful in identification, and we have included
colour reactions for simple spot tests which can help you to identify some of these species. These
spot tests are easy to do in the field and are described below.
Spot tests:
simple spot tests have been used for many years to identify lichen substances that have a
colour reaction. Note that a + denotes a positive colour reaction and a – indicates that there is no
colour change. If you want to use the substances in the field you only need very small amounts (c.
20cc) which can be put in eye dropper bottles and kept in the fridge when not in use. <br>
Sodium hypochlorite (C)
is common bleach, the thin cheap variety without any additives is the best.
Keep the bottle in the fridge if you want to use it repeatedly over several weeks. Avoid getting it on
your clothes.
Potassium hydroxide KOH (K)
or alternatively sodium hydroxide (NaOH - caustic soda) is used as
a 10% solution in water. Care should be taken preparing this as it is highly caustic in the concentrated
form.
Both these substances are applied as a small drop to the cortex, or to the medulla after scraping away
the cortex. Record the colour reaction carefully and any change in colour that occurs.
Paraphenylendiamine (P)
is not readily available except from a lab and is not recommended for use
outside laboratory conditions. It is available as crystals and can be dissolved in alcohol in order to
test the specimen. Alternatively it can be made into a stable solution for regular use called Steiner’s
solution. Instructions are available in most lichen identification books.
Negative reactions
: the liquid /or the treated part of the lichen does not change colour (however, the
surface may become more green).
