ESSEX   BOTANY   AND   MYCOLOGY  GROUPS 

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Centaurea cyanus L.                                                                                                  Cornflower                    ___________________________________________________________________________________

 Essex status: Long established alien with declining seed bank, casual and planted.

The Cornflower is generally regarded as a long established archaeophyte 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, though it would seem that we may have seen the last of any viable seed. Germination tests suggest 4-yrs as the viability limit, but there must either be a long tail to the distribution or local variants with a longer viability, as it clearly has occurred at intervals of much greater than 4 years at some sites. Any plants that do appear and seed today, however, are automatically eliminated from arable crops by herbicide and seed screening, and once the viability of the 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).

Probable seed bank occurrences only: