The Scarce Plants of Essex. Part 2.
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eutrophic ponds throughout the county, but is most abundant, and persistent, in brackish grazing marsh
drains, and borrow dykes behind the sea walls, where it commonly grows with Potamogeton pectinatus
and Ranunculus baudotii. Because it tends to be overlooked, it is probably under recorded around the
Essex coast. Where it does occur, it often does so in considerable quantity, filling the water column.
Despite its aquatic habitat it has a virtually identical national distribution to that of Bupleurum
tenuissimum, suggesting that both populations may be restricted to areas with high summer temperatures
(mean July > 15°C), possibly combined with low winter values (January mean