Changes in the status and distribution of Oenanthe pimpinelloides in Essex
In the case of the Little Haven Meadows EWT. NR, just south west of Rayleigh Weir, however, the
now well established colonies arose from an original Combi load derived from Burcart's Meadow
at Clacton. The relatively small colonies discovered at Gunners Park, Shoebury in 1998 (300 plants)
and the 12 plants on MOD grassland land nearby are a puzzle. Are they relicts of former long
standing 'native' sites, or recent accidental mowing machine introductions?
The same sort of story applies to the Tendring colonies. In the Essex Naturalist 17: 208 for 1913,
F. Saxer in his Flora of the Clacton District describes a colony 'just above high tide level,.....on
another depression of the soil Juncus maritimus could be seen in the company of Oenanthe
pimpinelloides.' Rather an unusual site, and hopefully not a mistake for O. lachenalii. In 1988
however Jerry Heath discovered two plants on a damp verge at Little Clacton. Subsequently a large
colony was located throughout a meadow to the cast of White Lodge, including new colonics on
both verges of a new road recently put through the northern half of the field (1995). Then in 1998,
David Bain found 12 plants in Burrsville Meadow Country Park, Clacton (used by the same tenant
farmer) and 3-4 plants in a maritime marsh meadow at Jaywick in 2002. The EWT has also managed
to introduce it inadvertently, with cutting machinery used at Burcarts, to Great Holland Pits N.R.
and Barnes Spinney N.R. It was also introduced to the Martin's Farm infill 'restoration' at St.
Osyth, as an insurance against losing the only presumed native site at Clacton. Wherever it is
introduced into existing meadows it seems to take off rapidly, and within 2-3 years forms huge
dominant patches.
It would therefore appear to be unfortunate that the Combi harvester, so useful for removing cuttings
from small meadow sites, and verge flails, are both deliberately and inadvertently being used to
introduce a plant poisonous to livestock to so many of our few remaining hay meadows. Although
there have been reported cases of cattle poisoning by O. pimpinelloides in Poland, so far there have
been no reports from the U.K. The Corporation of London in their management plan for Sheppard's
Meadow stipulate that the dropwort is not to be included in hay Unfortunately the active poison
oenanthetoxin (a polyunsaturated higher alcohol), which acts as a convulsant, is unaffected by
drying and storage. Most of the poison probably resides in the potato-like tubers that could be
exposed and eaten by livestock in over grazed meadows, and where dense drifts of the over ground
plants occur, animals destined for our food chain, fed on the hay from such fields, could have toxic
residues residing in their tissues after death.
Nowadays, gardening in the form of habitat creation and 'floral enrichment' seem to be taking over
from conservation of our remaining semi-natural hay meadows. To the botanist trying to establish
the semi-natural vegetation patterns across the county, the situation is a nightmare. By using the
same 'contaminated' machinery, widely throughout the county, we could end up inoculating every
bit of ancient grassland we have left, with a ubiquitous range of flowering plants and grasses, the
most dominant of which will pervade all our grasslands. Because O. pimpinelloides is so good at
coping with mowing and flailing it is joining Cow Parsley, Tall Fescue and Alexanders as a dominant
colonist on several of our roadside verges, and may well spread throughout the county over the
next decade or so. This begs the question of why it remained confined to so few sites prior to the
advent of machinery able to spread it far and wide. Was it confined to these few sites by local
climate? Did it fail to set enough seed? Or was it just that its seed was too heavy to spread far on its
own? Once established, being a perennial with tubers to fuel rapid regeneration if cut off in its
prime, it could become one of our commonest verge as well as meadow plants on neutral clays. It
seems to need bare ground to get established from seed but our dry summers and flail scuffing
probably provide the necessary bare spots to start it off on a new site.
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Essex Naturalist (New Series) 21 (2004)