Notes on Essex Specialities: 5: Sickle-leaved Hare's-ear Bupleurum falcatum L.
botanist reseeded the site in 1978. The plants had been exposed by scrub clearance on the back verge,
and ironically, shortly afterwards the road men burnt this scrub material on the very spot! As if to make
certain of its demise, the verges were sprayed with broad-leaved herbicide, all the way from Epping to
Ongar in 1980. The section of road along which it formerly grew is now a derelict cut-off, having been
isolated by a new bypass that comes within a few yards of the last known site of the plant.
B. falcatum is a biennial to short-lived perennial with umbels of bright yellow flowers that produce
nectar particularly attractive to hoverflies. The sickle-shaped leaves that give the plant its name are
produced only when the plant is heavily infested by frog-hoppers, which appear to damage the leaves
in some way, so that one half of the lamina develops more than the other. Seed is produced copiously,
but is only viable for a year at most. Young seedlings appear in May, largely around parent plants, but
arc unable to compete in a closed sward. They prefer thermophilic, dry, bare, calcareous, mineral-soils
with minimal humus. On the continent its distribution extends across southern, central and eastern
Europe, and northwards to Belgium, Germany, Poland and central Russia. The northern localities,
however, are rather scattered although it is plentiful in nearby coastal north-west France. It could
therefore have arrived here on its own on a muddy bird's foot, and thus be truly native. It is just as likely
however to have started out as a crop seed contaminant in fresh seed imported from France in the late
18th or early 19th century. On the continent it colonises harsh habitats on dry sunny slopes and ridges,
and the scrubby southern margins of woods, - on calcareous clayey and sandy soils. Elsewhere in the
British Isles it has been reported only as an ephemeral casual, once each at Reigate Heath and Wandsworth
(Brewer 1863) although it is widely grown in botanic and private gardens. Unfortunately Stanley
Jermyn's 'insurance' colonies on the Fingringhoe Wick reserve have both died out.
Fig. 2. Bupleurum falcatum © Chris Gibson
Mericarps of B. falcatum subsp, falcatum
have however been found as sub-fossils in
Pleistocene temperate interglacial deposits, at
Frog Hall in Warwickshire and at Somersham
in Cambridgeshire (Field 1994). At the time
these were both believed to date from the last
(Ipswichian) interglacial [and not 'Flandrian
interglacial deposits' as it ended up in Adams
1999b, instead of the 'last interglacial before
the Flandrian']. Since that however, amino
acid determinations from the Frog Hall
deposits have yielded ratios compatible with
Oxygen Isotope Stage 9, (Keen et al. 1997),
and therefore probably belong to the Hoxnian
sensu Bowen (1999), whereas the Somersham
material is still considered to be from the last
(Ipswichian) interglacial (OIS 5e) (West et
al 1999).
For the Norton Heath colony to be a relict
from a wider Ipswichian distribution it would
have had to survive the subsequent glacial or
periglacial conditions of the Devensian, an
unlikely scenario for such a southern species.
Essex Naturalist (New Series) 18 (2001)
159