<ul>
<li>This account presents information on all aspects of the biology of <em>Primula elatior</em> that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the <em>Biological Flora of the British Isles</em>: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation.</li>
<li><em>Primula elatior</em> is a native perennial herb, within a compact area in the British Isles, in ancient woods and copses on the chalky boulder clay in East Anglia, where it is abundant locally although scarce nationally. British material is ssp. <em>elatior</em>, which extends across much of Europe, becoming rarer towards the south.</li>
<li><em>Primula elatior</em> is a shade tolerant species, but only flowers in profusion in the increased light levels following tree felling in traditionally coppiced woods. It is confined to an area of the British Isles where the soils are seasonally waterlogged and ill-aerated, and is very tolerant of the toxic levels of ferrous iron which accumulate in the surface horizons in the spring months. It has a poorly developed drought tolerance.</li>
<li>An early flowering plant, <em>P. elatior</em> is an insect-pollinated obligate outbreeder, with two self-incompatible morphs (pin and thrum). The low colonizing ability of this ancient woodland species can be attributed to both seed dispersal and seedling recruitment limitation.</li>
<li>There has been a steady reduction in the density of <em>P. elatior</em> in woodland sites during the past centuries. However, there has been little change in the 10-km distribution in the British Isles. Studies of populations involve three groups of factors: genetic variation, environmental changes and population structure. Potentially these factors have a greater effect on small and isolated populations than on large and integrated ones. There is no evidence that the species suffers from a loss of genetic diversity in the smaller populations. <em>Primula elatior </em>seems to have a relatively high level of genetic diversity that is maintained despite a fragmented distribution.</li>
<li>Within its restricted distribution area <em>P. elatior</em> replaces <em>P. vulgaris</em> completely. At the margins of their distributions the two species occur together in a number of woodland sites, providing the opportunity for hybridization. As they are highly interfertile, hybridization is restricted mainly by differences in their habitat preferences. The hybrid <em>P</em>.<em> vulgaris</em> × <em>P. elatior</em> = <em>P.</em> × <em>digenea</em> is fertile and gives rise to hybrid swarms which are found in all British sites where both parents occur together.</li>
<li>Changes in climate, woodland management practices and intensities of deer grazing, especially by Fallow deer (<em>Dama dama</em>), are likely to have a major effect on populations of <em>P. elatior</em>. Since the species colonizes new or secondary woodlands very slowly, management should focus on the conservation of ancient semi-natural woodlands.</li>
</ul>
