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Summary1. This account presents information on all aspects of the biology of Primula vulgaris Huds. (Primrose) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the framework of the Biological Flora of the British Isles : distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characteristics, herbivores and disease, history and conservation. 2. Primula vulgaris is a native perennial herb with a very wide distribution in the British Isles. In many lowland areas it is essentially a plant of woodlands and hedgerows, although in the west it can occur abundantly in grasslands and other communities such as heaths. In northern and western Britain and Ireland, it may be frequent in open and even exposed habitats. Its distribution is linked with soil moisture and atmospheric humidity. It is shade tolerant, but it flowers most profusely in canopy gaps. 3. Primula vulgaris is a rosette hemicryptophyte that reproduces mainly through seeds. Vegetative spread is restricted and only occurs within very short distances from the mother plant through the production of lateral rosettes. Although individual rosettes may die, plants are relatively long-lived (life expectancy of a newborn individual: 48.3 years). The mean age at first flowering was 20 months. 4. Pollination is mainly by bumblebees and other bees, but other long-tongued pollinators including syrphids, bee-flies and even butterflies may be locally important. P. vulgaris is an obligate outbreeder, with two genetically determined self-incompatible morphs ('pin' and 'thrum'). A third morph ('homostyle' or 'long homostyle'), with a stigma like that of pin but anthers like that of thrum, has been found in Somerset and North Dorset. In years when pollinators are scarce, homostyles have higher reproductive success than pins and thrums, suggesting that reproductive assurance could have had a profound effect on the evolution of homostyly in P. vulgaris . 5. Seeds are dispersed by ants and rodents. Dispersal is usually restricted to a few centimetres or decimetres from maternal plants, resulting in significant fine-scale spatial genetic structure and small neighbourhood sizes. Pollen flow, on the other hand, is more extensive, but still limited to a few metres from paternal plants. 6. Populations of P. vulgaris have not changed markedly during the last century in most parts of Britain and Ireland and it is not threatened with extinction nationally. However, there is evidence †Correspondence author: E-mail: hans.jacquemyn@bio.kuleuven.be ‡Deceased *Nomenclature of vascular plants follows Stace (1997) and, for non-British species, Flora Europaea . that Primroses were formerly more widespread and have decreased with the decline of coppicing and pollarding. In East Anglia, woodland populations have declined greatly in response to a series of hot, dry summers since 1970. Small, isolated populations of P. vulgaris often show reduce...

Summary1. This account presents information on all aspects of the biology of Primula elatior that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles : distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation. 2. Primula elatior 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. elatior , which extends across much of Europe, becoming rarer towards the south. 3. Primula elatior 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. 4. An early flowering plant, P. elatior is an insect-pollinated obligate outbreeder, with two selfincompatible morphs (pin and thrum). The low colonizing ability of this ancient woodland species can be attributed to both seed dispersal and seedling recruitment limitation. 5. There has been a steady reduction in the density of P. elatior 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. Primula elatior seems to have a relatively high level of genetic diversity that is maintained despite a fragmented distribution. 6. Within its restricted distribution area P. elatior replaces P. vulgaris 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 P . vulgaris × P. elatior = P. × digenea is fertile and gives rise to hybrid swarms which are found in all British sites where both parents occur together. 7. Changes in climate, woodland management practices and intensities of deer grazing, especially by Fallow deer ( Dama dama ), are likely to have a major effect on populations of P. elatior . Since the species colonizes new or secondary woodlands very slowly, management should focus on the conservation of ancient semi-natural woodlands.