The distribution of the Oxlip Primula elatior (L.) Hill in Essex
The number of Oxlips
For each site surveyed, an estimate was made of the number of plants present. Although this is
mainly intended to provide base from which to measure future change, the figures do offer the
opportunity to look back and estimate the scale of change that has occurred. Memory is notoriously
fickle, and although everyone remembers woods yellow with Oxlips, it is impossible to put any
numeric scale to this. Even the estimates made on these surveys have an error factor. One cause of
error lies in what a surveyor perceives as an Oxlip plant. Trials (Tabor 1998) have shown that Oxlip
seed is naturally dispersed only between 3cm and 15cm from the parent plant, resulting in very
close aggregations of plants. Mature plants have a rhizome that can produce four or five rosettes of
leaves (Browne 1995). It is thus extremely difficult in the field to separate rosettes from the same
plant (ramcts) from rosettes from different plants (genets). The figures in this survey arc simply
numbers of rosettes; as such they will over estimate the total numbers of plants.
That said there are a very few sites where it is possible to get a glimpse of the changes that have
occurred. The first of these is Hempstead wood, for many years recognised as the most prolific
Oxlip wood in the country. Jermyn (1974) stated '... the plant is fairly evenly distributed over the
greater part of the 175 acres. An estimated average number of plants is approximately 4,500 plants
to the acre, which gives a population of about three-quarters of a million Oxlips!' Rackham (1975)
said that Hempstead had twice as many Oxlips as Hayley wood, which at that time had in excess of
a million plants. The real difficulty in separating ramets from genets may account for the difference
in these estimates. Figures for Hempstead in 2002 resulting from a number of transects through
neglected, coppice and coniferised areas, reveal a population of no more than 30,000 plants.
Peverel's Wood was a site on which Christy (1884) did a lot of his work. His estimate, carried out
inApril 1883, was that in the cut coppice there were 14.43 plants per square yard. Since the coppice
plot was 88 x 440 square yards (8 acres), he calculated a population of 558,730 plants just in the
coppiced area. The 2002 survey estimated that only 4,500 plants remain in the entire 36 acre wood.
Finally let us consider the meadows at Bardfield. Doubleday (1842) quotes '...in one instance a
meadow of about two acres is entirely covered by them (Oxlips), being a very mass of yellow
bloom.' If plants were spaced one foot apart there would be over 40,000 per acre, so it is unlikely
to have been less than 50,000 plants on the two acre meadow. There arc less than 15 plants in the
whole of Bardfield village now.
Table 3. Numbers of sites by type together with the approximate numbers of plants they contain.
(Numbers of plants are calculated from the median number of the range within which each site was
scored).
Essex Naturalist (New Series) 19 (2002)
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