This year marks the 25th anniversary of RBG Kew's Millennium Seed Bank (MSB), based at Wakehurst, Sussex. Since Kew began collecting seeds to store for conservation in the mid-1970s, nearly 2.5 billion seeds from over 40,000 species have been carefully cleaned, dried and stored in walk-in freezers at minus 20 degrees Celsius.
The MSB's mission has become more crucial than ever. Recent estimates by Kew scientists indicate that 45% of all flowering plants worldwide are currently at risk of extinction. As global challenges intensify, the MSB serves as a vital safeguard for the future of both the planet and humanity.
The renowned naturalist Sir David Attenborough underscored the importance of this work, calling the Millennium Seed Bank ‘perhaps the most significant conservation initiative ever’.
Protecting UK plants
While focused globally, the MSB's work also includes dedicated efforts to collect and store rare and endangered plant species right here in the UK.
‘Seeds may be tiny, but they are of monumental importance to us all.’ - Cate Blanchett
1. Starved wood-sedge (Carex depauperata)
This species has always been rare in Great Britain, and grows naturally along the edge of woodlands. It’s now only found at a couple of sites in England and has probably suffered due to a decline in traditional woodland management, such as coppicing. We’ve been running field and lab trials to try and understand the seed germination requirements under different temperature and light regimes, with some interesting results. Rather unexpectedly for a UK species we found that the most germination occurred at over 30 degrees Celsius.
2. Pheasant’s eye (Adonis annua)
This rare cornfield annual earned its name from its striking flowers which resemble the eye of a pheasant, and is an ancient introduction to the UK known as an ‘archaeophyte’. It grows in disturbed habitats, including traditionally managed arable farmland. However, the introduction of modern farming techniques contributed to the species’ decline.
We’ve been working to conserve pheasant’s eye for many years, including carrying out germination trials to crack complex seed dormancy, and sharing the findings through the Colour in the Margins project, led by Plantlife.
3.Dwarf milkwort (Polygala amarella)
Growing to a maximum height of just 20cm, dwarf milkwort is found growing in chalk and limestone grassland and mires. It has been impacted by habitat loss, particularly in south-east England. Around half of the species’ UK sites have been lost, mainly due to undergrazing of chalk grassland.
In response to this, we are working in partnership with the Species Recovery Trust and Kent Wildlife Trust to increase the number of plants in Kent. We are now seeing natural regeneration at one of the trial sites, which is a great sign that this introduced population is establishing and hopefully will increase in years to come.
4. Broad-leaved cudweed (Filago pyramidata)
Another species which prefers habitats with regular disturbance, broad-leaved cudweed is now restricted to very few sites and requires careful management as it struggles to tolerate competition from other plants.
In 2021, we grew around 100 plants in the nursery and produced over 600,000 seeds which over several years are being sown into a prepared field in Oxfordshire in an effort to bolster the existing population. So far, it’s going pretty well, but the seeds are tiny (5,000 seeds weighed only 0.21 grams), which made handling them a bit tricky.
5. Petty whin (Genista anglica)
This small shrub is found in heathlands and on the edges of damp habitats such as mires and bogs. Its threat status has recently been upgraded to Endangered in Great Britain, which reflects the reduction in area in which it is found. This new assessment represents a big increase in the level of threat and urgency needed to conserve the species.
We are currently working with Natural England in the north of England to support petty whin, growing seeds and cuttings collected this summer in the MSB glasshouses. When the plants have grown larger in the nursery, they will be planted out to boost the population where they were collected.
Learn more about the MSB and its work
Listen to the new podcast series with Cate Blanchett, Unearthed: The need for seeds, available now wherever you listen to podcasts.
