The Rusty Backed Fern
by Brian Darnton, UK
Objects for microscopic study are more numerous than we might
imagine. It only requires a knowledge of which method of
observation we should use, to convert some dull rusty looking
object into an optical treasure house. The Rusty Backed Fern is
one of those plants!
It grows throughout the more
sheltered areas of the British Isles and across Europe as far
North as Holland. Similar species can also be found in Asia.
Older books often list it as Asplenium ceterach. It enjoys
the cracks between stones in the ruins of castles and old
limestone walls where there is free drainage. Hold a clean sheet
of paper under the leaves and scrape some scales from the
underside of a leaf.
The collecting paper can be folded , labelled and taken home
where the scales can be sorted under a good hand lens or low
power microscope. A rosette of 7 scales can be assembled on a
blank slide in a weak dilution of Gum Tragacanth. Under a warm
lamp the rosette can be dried out, a drop of Canada Balsam
applied and a cover slip laid.
Under a X10 objective lens
and a microscope equipped with two crossed polarising filters the
reason for all the preparations will be revealed. The delicate
framework of the scale glows as a reticulate pattern. When dried
out and ringed, it should be labelled; including such information
as where it was found and how it was prepared. A variety of ferns
have interesting scales, but it is mostly those that are adapted
for life in dry places that are the most fascinating. In the
southern parts of the United States and in Mexico the Cloak fern
(Astrolena sinuata) has fine scales and in the West
Indies, Niphobolus has stalked whorls of minute scales
like a microscopic moss.
Comments to the author Comments to the author sent via our contacts page quoting page url plus : ('bdarnton','')">Brian
© Microscopy UK or their
Published in September 1998
Please report any Web problems
or offer general comments to the Micscape Editor,
via the contact on current Micscape Index.
Micscape is the on-line monthly
magazine of the Microscopy UK web
site at Microscopy-UK
© Onview.net Ltd, Microscopy-UK, and all contributors 1995 onwards. All rights
reserved. Main site is at www.microscopy-uk.org.uk with full mirror at www.microscopy-uk.net.