11.
Two weeks later the mud had dried out
sufficiently for Owen Mountford to get close
enough to identify it as the Hampshire Purslane
(Ludwigia palustris (L.) Elliot), now otherwise
confined in Britain to the New Forest.
Unfortunately the Forest authorities took
advantage of the dry conditions to dredge the
pond which was rapidly being over-run by Typha
and Iris beds and the two feet or so of black
ooze was removed down to the basement gravel.
Although some pieces of Ludwigia were rescued
and reintroduced to the pond subsequently, it
would seem unlikely that they will survive,
as apart from the fact that this species
seldom overwinters in the vegetative state in
this country, the nutrient status of the water
has been drastically altered. It is also
unfortunate that the bay of the pond where the
last remaining thalli of Ricciocarpus natans
(the least common of our floating liverworts)
in the Forest survived, was also excavated down
to the gravel bed despite advice to the
contrary from the Epping Forest Conservation
Centre staff. Fortunately this species, which
is very scarce nationally, was discovered in
Dagnam Park by Peter Wanstall last year, so
it is not yet lost to Essex, though I fear we
shall not see it again in Epping Forest this
century.
As the summer progressed Oak Pond at High
Beach, already bone dry, began to grass over
and a large patch of Polygonum species
appeared in the middle, including: P. Persicaria.
P. lapathifolium and P. hydropiper. Owen
Mountford, while listing plants growing in the
pond, came across a plant of Polygonum minus in
this patch, and subsequent searching revealed
a further seven scattered plants. This species,
like Ludwigia flourishes and fruits most pro-
lifically on wet mud in warm situations and
has not been reported in Essex since Gibson's