Bluebell flowering times can be used as powerful evidence of climate change.
That is why the aim of this survey is to build up a nationwide picture of when bluebells, both native and non-native species, start flowering each year.
The study of the timing of events is called phenology and it can provide important evidence for climate change, particularly if information is gathered over long periods of time.
The flowering dates of such widespread and familiar plants as bluebells have been recorded for many years, but not always very systematically and only in a few areas.
This survey will allow us to capture this vital information from all over the country so it can be studied by scientists.
By comparing recent survey results with past data we can find out whether the flowering season is changing.
However, our bluebells, like the climate, have changed over time. In recent years there has been growing concern that our native species is under threat by breeding with non-native bluebells – a process called hybridisation. This alters a plant species’ genetic makeup, including when it flowers.
To be able to make fair comparisons with data from previous years, we need to know whether an earlier flowering season is caused by changes in the flowers themselves or changes in the climate.
We also need to know which species of bluebell we are looking at because non-native bluebells, which originated further south than the native species, may flower earlier in the year.
This means it is important to identify whether the plants are natives or not when recording bluebell flowering times.
In the UK there are several different types of bluebell. The familiar native bluebell, Hyacinthoides non-scripta, is characteristic of woodlands, hedges and other shady places, and almost half the world's population of this species is found here.
We also have non-native bluebells. Flowers that have been called the Spanish bluebell, Hyacinthoides hispanica, are mostly a horticultural form of the plant. They have one more set of chromosomes, pieces of DNA, than the native bluebell. They are widely cultivated and can be found in many urban settings such as gardens and parks. The true Spanish bluebell is also cultivated but more rarely.
A hybrid bluebell, Hyacinthoides x massartiana, formed between the native and Spanish forms now appears to be more common than its Spanish parent; it is increasing and has completely replaced the native bluebell in some urban areas.
This survey will compare the flowering seasons of the native and non-native species of bluebell (non-natives include both Hyacinthoides x massartiana and Hyacinthoides hispanica).
Our survey will collect data on when bluebells start to flower each year in different parts of the British countryside. Over time, this data will give us the evidence we need to document climate change. It will also help scientists model the possible effects on our flora and fauna.
The easy-to-use identification guide and online recording form enables everyone, from children to scientists, to contribute to this annual survey. Results are shown in an online interactive map.
The survey builds on the information collected by the public since 2006. By collecting data over many years we can form a more accurate picture of what is happening, so we hope you will take part every spring.
The information will help us understand and document the ongoing changes both to our bluebells and to our climate. The results of the survey will also form a vital part of the Museum's science research programme and contribute to scientific publications.
If you want to buy native bluebell bulbs for a garden, try to ensure they are from a reliable source and have been raised in cultivation, not stolen from the wild. If in doubt, do not buy them.
Do not knowingly plant Spanish or hybrid bluebells in the countryside.
Never throw away rubbish containing garden bluebell bulbs 'over the garden fence' or onto outdoor tips or dumps. Remember that compost heaps may not destroy the bulbs.
It has been illegal (without a licence) for anyone to collect native bluebells from the wild for sale since 1998. This is because native bluebells are listed on Schedule 8 of the Wildlife and Countryside Act (1981).