clicking on the box again, you can check if it is in the centre. Within a few seconds you
will find that you can get the little cross-wired box spot-on the point for which you
require a grid reference.
I have been using this technique to get accurate grid refs for the centre of the canopies of
individual Black Poplar trees and Mistletoe host trees. By printing off a high resolution
print from Google Earth of the area you are surveying and marking up features on it with
a pen in the field, you can then rcfind these points on-line, and get an accurate grid ref.
for them without the +-30m error inherent in a hand-held GPS reading, and the fact that
short of cutting down the tree you can't stand where the trunk is.
Before tackling books and web sites on the lower plant groups I must mention two new
higher plant books just out. Richard Lansdown has produced the long awaited Water-
Starworts of Europe. BSBI handbook No: 11. 2008. BSBI. The first to cover all the
species of a genus Europe wide. No excuse for Callitriche agg. crossings through on
your cards from now on! And just this week Vol: 3 of the exhaustive Flora of Great
Britain & Ireland by Peter Sell & Gina Murrell, - covering the Mimosaceae to the
Lentibulariaceae has arrived. Confirming amongst other things that all those odd looking
'Field Maples' that we see planted everywhere are indeed non-native and are seeding all
over the place, whereas our native var. campestre is not reproducing itself. With eleven
forms of the Field Bindweed Convolvulus arvensis to play with, and covering 21 species
of Acer we shall all have to look at our plants much more carefully. The authors are to be
congratulated for putting up with yet another CUP cock-up. The original print run had to
be destroyed as it was the uncorrected proof version! Perhaps CUP had a premonition
and that's why they pre-priced it at a ridiculous £130.
Books on freshwater algal identification
The algae, despite their importance as photosynthesizers in the aquatic food chain, and
in some cases the source of highly toxic compounds in both fresh and sea water, are a
very neglected group amongst the amateur naturalist community. First of all some
terminology: it never ceases to irritate me when I hear BBC/ITV newscasters, science
documentary commentators, or see adverts/articles in New Scientist! - misusing the
terms 'bacterium' (singular), 'bacteria' (plural) and 'bacterial' (adjective). The same
problem arises with the equivalent terms; alga (s) algae (p) and algal (a); and for that
matter fungus (s), fungi (p) and fungal (a). A further problem in the case of the algae is
that we now know that a whole group of them, formerly known as the Blue-green Algae
or Cyanophyceae; are really just souped up photosynthetic bacteria - more properly
now known as the Cyanobacteria. Despite this revelation algologists still claim them as
theirs. Thus the most authoritative mighty single tome on the algae The Freshwater
Algal Flora of the British Isles (An identification guide to freshwater and terrestrial
algae) edited by D.M.John, B. A.Whitton and A. J.Brook. The Natural History Museum.
CUP. 2002. - includes the 360 or so Cyanobacteria recorded for the British Isles, but, it
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Essex Field Club Newsletter No. 59, May 2009