patch of Flowering Rush, Butomus umbellatus; and only a single small patch of
Potamogeton lucens, very tatty and shredded, was located along the whole stretch, -
some 200m west of the weir. The only appreciable bank-side and shallow, marshy
vegetation was on the south side of the canal which fortunately is still grazed by cattle.
Even so, only a single clump of Great Water Dock is now left along this section of the
canal. Further down, just before the weir leading to a meander of the old river, the motor
cruiser Victoria, now back in service, following an impressive, massive, local effort to
clear the rafts of the alien American Pennywort, Hydrocotyle ranunculoides, - did a
pirouette by the weir to return upstream, well loaded with jar-swinging revellers, -
recalling our own more sober EFC outing back in 1981 (Essex Field Club Bulletin 25)
when we sampled the canal from the Victoria, in the days when it was still a richly
vegetated waterway. On the way back to Hoe Mill, we came across the clump of a
perennial alien Euphorbia reported in the Flora of Essex by Stan Jermyn. Stan was
unable to put a definite name to it, and even in 2006 we are stumped, as it does not fit
any of the descriptions of members of the E. esula aggregate given in the Plant Crib
1998.
We have still to explore the section from the weir down stream to Beeleigh, but the
submerged macrophytes along the rest of the Canal would seem to be well on their way
to being exterminated, presumably due to the increase in motorized boat traffic, and the
canal may soon be as sterile as the Stort and the Lee, the Pondweeds P. perfoliatus and
P. lucens joining the long list of extinct Essex plants. Even in 1981, there was no emergent
vegetation, everything having been chewed off to screw depth, but there was still plenty
there at depth. What a shame this superb waterway could not have been preserved as a
heritage site, the towpath renovated and hircablc horse-drawn barges reintroduced as a
heritage feature. Unfortunately, nowadays it costs a fortune to maintain these old canals.
The deterioration in the vegetation since 1981 may not all, however, be due to boat
traffic. Somebody prior to 1990 introduced the alien American Pennywort, Hydrocoytle
ranunuloides to the Chelmer in Chelmsford, and it rapidly proliferated and spread
downstream, forming vast floating rafts that blanketed the canal surface, and has cost a
fortune in human effort to clear from the canal. It may well have cut-off the light and
contributed, hopefully, to just a temporary decline in the submerged aquatics.
Peter Wilson supplied the flowing list of molluscs obtained with the chuck bucket from
the main channel. Species found live are in both bold and italic, as fresh shells, just in
italic, and as old shells in regular type: Theodoxus fluviatilis, Valvata cristata, V.
piscinalis, Potamopygus antipodarum, Bithynia tentaculata, B. leachii, Physa
fontinalis, Physella acuta, Lymnaea stagnalis, L.peregra, Planorbis carinatus, Anisus
vortex, Gyraulis albus, G. crista, Hippeutis complanatus, Ancylis fluviatilis, Acroluxus
lacustris, Sphaerium corneum, Pisidium amnicum, P. casertanum, P. milium, P.
subtruncatum, P. supinum, P. henslowanum, P. nitidum, P. moitessierianum. The general
lack of any numbers of molluscs, in particular Limnaea stagnalis, so abundant in 1981,
give some indication of the decline in main channel vegetation.
22 Essex Field Club Newsletter No. 52, January 2007