straight sides; whereas in C. salebrosum they bulge out slightly above to give a pyriform
shape.
So far we have not found C. salebrosum in Essex, or in Suffolk. If you know of a
Conocephalum sp. colony in Essex, please either let me have a grid reference, or better
still, a live specimen as well (in non-crushable container with some damp tissue). I have
a list of about 40 colonies in Essex but only a few of these have been revisited to check
them out. We are not just looking for the new species; we need to confirm the distribution
of C. conicum sensu stricto as well.
Stream & River Water Crowfoot - two neglected species
Ken Adams 63 Wroths Path, Baldwins Hill. Loughton. Essex. IG10 1SH
Water Crowfoots are the white-flowered relatives of our yellow buttercups, and belong
to the same genus; Ranunculus. Of those found in Essex; four species have flat, (laminate)
floating leaves together with fine bifurcating, cylindrical, underwater-leaves; and three
of them only have these capillary-segmented submerged leaves. R. aquatilis (Common
Wc) is probably the commonest of the first category, though it is declining rapidly as
our livestock drinking ponds are being abandoned to scrub encroachment, polluted or
filled in. In less nutrient rich ponds, the larger flowered R. peltatus (Pond Wc) replaces
it. The two can be separated by the shape of the yellow nectaries at the base of their
petals, rounded in the former and pear-shaped in the latter. They can hybridise with each
other and with the third member of this group, R. baudotii (Brackish Wc), which has
half-moon shaped nectaries. The latter is characteristic of open, reasonably clean water,
brackish dykes. It is, however, less common (due to mis-identification) than the records
would lead us to suggest. In fact, R. aquatilis is probably the commonest crowfoot in
our brackish dykes. Finally we have the Ivy-leaved Water-crowfoot, R. hederaceus.
This species requires seasonably wet, soggy habitats with some water flow through the
ground, and tends to be rather sporadic, often exploiting ephemeral habitats or lying
low as seed for decades until scrub clearance lets the light in to a scrubbed over marshy
area. It often flowers as early as April and can therefore get overlooked.
Of the species which only have capillary-segmented leaves, R. trichophyllus (Thread-
leaved Wc) is by far the most widespread, being found in ponds ditches and slow flowing
streams. It has rather small flowers, with widely separated petals bearing semi-lunate
nectaries, and its compact capillary leaf-segments collapse into a blob when they are
taken out of the water. Its stems are also a bit rough with hispid hairs. R. circinatus
(Fan-leaved Wc) on the other hand, has rigid capillary leaves that form a flat circle that
retains its shape when taken out of water. It's a widespread but local species of rivers
ponds and lakes in more open habitats.
Essex Field Club Newsletter No. 49, January 2006
19