158
Centaurea cyanus L.
The Scarce Plants of Essex. Part 2.
Cornflower
Essex status: Long established alien with declining seed bank, casual and planted.
The Cornflower is generally regarded as a long established crop alien from south eastern Europe. It
was widespread and abundant in Gibson's day, but it no longer occurs in established populations in
Essex, and is most often seen as an introduction in 'wild flower' seed mixes on road verges, or as a
casual on tips and waste land. A substantial seed bank appears to persist, however, in the deep plough
layer of arable fields throughout the county, and occasional deep ploughing or excavations on arable
land bring it to the surface to germinate. Germination tests suggest 4-yrs as being close to the viability
limit, but there must either be a long tail to the distribution or local variants with a longer viability, as
it clearly occurs at intervals of much greater than 4 years at some sites. The heavy seed is not readily
dispersed, and any plants that do appeal" and seed today are automatically eliminated from arable crops
by herbicide and seed screening, and once the viability of the arable seed bank is used up it will
inevitably disappear from the county. Only occurrences of probable seed bank origin have been listed
here. There are numerous records of odd casual plants and ephemeral wild flower mix occurrences on
verges. Cornflower is now so rare in Britain as a resident cornfield weed that it has been transferred to
the Red Data Book (Wiggington 1999).
All records:
TL(52)51 552,172 19 Hatfield Broad Oak, arable field, a few plants on soil upturned for culvert
emplacement, absent the following year. 1982. George Smith.
TL(52)60 65,01 18 Margaretting, 3 plants in set-aside field. 1990. Graham Smith.
TL(52)70 18 Lingwood, nr Chelmsford, cornfield, date? (Jermyn 1974).
TL(52)72 73 ,297 19 Rayne, Rotten End (Wethersfield?), plentiful, cornfield, where it has
persisted for many years, date? (Jermyn 1974).
TQ(51)88 18 Dawes Heath, in clover field, date? (Jermyn 1974)
TL(52)81 833,108 19 Wickham Hall Cottages, cornfield opposite, quite extensive, and
further up the road on the opposite side going towards Langford,
after deep ploughing the previous winter. 1983. Mrs Jane Chavc
[now gone].
TQ(51)99 18 Canewdon, cornfield, date? (Jermyn 1974).
TM(62)12 154,293 19 Bradfield, 3 plants on grassy banks of small new farm reservoir,
just off Daily House Lane, soil turned up during reservoir construction.
1980. Monica Dilmas.
TM(62)02 19 Ardleigh, cornfield, date? (Jermyn 1974).
Ceratophyllum submersum L.
Essex status: Native, stable.
Unarmed or Soft hornwort
This Hornwort is commonly overlooked, because of a supposed difficulty in identifying it, but its soft
texture and bright green colour arc usually enough to alert the eye in contrast to the harsh, rigid, grey-
green C. demersum, and its identity is readily confirmed by the 3-4 (as opposed to 1 -2) forked, scarcely-
toothed leaf segments, and conspicuously warty fruits that are longer than the persistent style, and lack
the two basal spines of the other species. In Essex it is thinly scattered, though often ephemeral, in
Essex Naturalist (New Series) 17 (2000)