Saving the world’s rarest plant
Beacons Hawkweed Hieracium breconicola is one of the rarest plants on the planet. Prior to our species recovery project, the total world population comprised a single lonely plant. This last remaining plant maintained a tenuous foothold on a windswept mountain ledge in the Brecon Beacons National Park. Fortunately, Kew Gardens had seeds in storage at the Millennium Seed Bank and this allowed us to take up the challenge of saving Beacons Hawkweed from extinction. Following consultation with Kew, seeds were taken out of cold storage and sent to our rare plants nursery. We successfully germinated the seeds and created a backup population in cultivation. We began to return plants to the wild in 2021. It is hoped that by restocking areas that are beyond the reach of hungry sheep a new self-sustaining population will become established on inaccessible cliff ledges. Initial indications are very encouraging, many of our introduced plants have successfully established and are now flowering.
Resurrecting an extinct species
York Groundsel Senecio eboracensis is an English endemic that was once known from many locations around the City of York. It typically grew on waste ground next to railway lines and car parks as well as abandoned brownfield sites and as a pavement weed. The redevelopment of brownfield sites and the increased usage of herbicide by the city council caused a swift decline and the species became globally extinct in 2003. No plants were held in cultivation and the species only survived as seeds that were being held in long-term cold storage at Kew’s Millennium Seed Bank. The Rare British Plants Nursery has recently commenced work on an exciting project that will resurrect York Groundsel from extinction and return it to its historical haunts. The Millennium Seed Bank have provided us with seeds and these have successfully germinated at our nursery. We will soon have a substantial number of York Groundsel plants in cultivation and these will be used to founder new populations. We are currently identifying suitable sites that could support introduced populations. York Groundsel’s scuffle with extinction is almost over and its little yellow flowers will soon grace the City of York once more.
This rare endemic Hawkweed grows at a number of locations along the River Irfon in Mid Wales. It is typically found growing on rocky ledges close to the river. We recently surveyed all of the historical sites for Llanwrtyd Hawkweed and have found that the population has declined from over one hundred plants in 2008 to just twenty-three in 2022. The reasons for this decline are unclear but could relate to more regular flooding events and increased recreational pressure. We are establishing new populations of Llanwrtyd Hawkweed along the River Irfon as part of a river catchment restoration project funded by the Welsh Government.
Brecon Dandelion is endemic to Wales and is found nowhere else in the world. It was once known from a dozen sites in Monmouthshire and Breconshire but has been lost from most of these as a result of changes in land management and overgrazing by sheep. It is now critically endangered and threatened with extinction. We have just commenced work on a species recovery project that will establish new populations of Brecon Dandelion in the Brecon Beacons National Park. Kew’s Millennium Seed Bank supplied us with seeds and we now have a back-up population of the Brecon Dandelion in cultivation. We have identified a number of sites that could support this special Dandelion and we will be introducing cultivated plants to these locations early next year.
The Great Fen Restoration Project
Water Germander Teucrium scordium is a very rare wetland plant. Agricultural intensification has caused the extinction of most British colonies and it is now known from just two British sites. As part of The Great Fen Restoration Project, we are working with Natural England to return Water Germander to its former haunts in the Cambridgeshire Fens. We are currently cultivating five hundred Water Germander plants that will be returned to the wild later this year.
As well as cultivating rare plants for species recovery projects, our plant nursery is also a botanical storage facility. We have a number of ongoing projects involving rare plants that have been rescued from development sites and require temporary storage. We are currently looking after two hundred Northern Marsh-orchids Dactylorhiza purpurella that were removed from a site in Warrington prior to the construction of an industrial warehouse. As part of the development’s conservation strategy a new habitat is being created for the orchids. We have been commissioned to look after the orchids whilst their new habitat is being created.
An endemic Hawkweed on the cusp of extinction
Hepste Hawkweed Hieracium apheles is endemic to the Hepste Glen in the Brecon Beacons. Until recently it was presumed to be extinct as it hadn’t been seen since 1896. Hawkweed experts from the National Museum of Wales undertook a targeted search of the Hepste Glen in 2010. To their delight they found one small population of Hepste Hawkweed growing close to where it had last been seen one hundred and fourteen years previously. A total of five plants were found, all in close proximity growing on a rocky ledge next to a small waterfall. Any chance event could eliminate such a tiny and critically endangered population and so conservation action was urgently required. In consultation with the site owners, we collected seeds from the wild plants and grew them on in our plant nursery. Sixty of these cultivated plants were returned to the Hepste Glen in summer 2021. Initial results are promising and most of the introduced plants have survived their first twelve months in the wild.
Limestone Woundwort Stachys alpina is a perennial herb that is now restricted to just two sites in the British Isles, one in Denbighshire in Wales and one in Wotton-Under-Edge in Gloucestershire. A local wildlife charity in Gloucestershire asked if we could help establish a backup population for the Wotton plants. Our rare plant collection already included Limestone Woundwort with Wotton provenance so we were able to get to work immediately. A churchyard not far from the existing native site was identified as an ideal receptor site. Following consultation with the resident vicar and her parishioners, Limestone Woundwort plants were introduced in autumn 2021. This newly foundered population is now flourishing under the existing churchyard management regime.
Historically this rare Hawkweed was known from two sites in the Brecon Beacons but it is now only known from one. Just a few years ago the last remaining locality at Pwll Byfre supported almost two hundred plants but the population has now crashed to just ten individuals. The reasons for this sudden crash probably relate to increased sheep stocking densities. The Millennium Seed Bank supplied us with seeds and we now have a back-up population of Crass-leaved Hawkweed in cultivation. We will be retuning plants to its historical site at Fan Nedd early next year.
Rock Cinquefoil & Sticky Catchfly
Criggion Quarry, Breidden Hill, Montgomeryshire
Breidden Hill is a famous site for very rare plants including Rock Cinquefoil Potentilla rupestris and Sticky Catchfly Silene viscaria. At Breidden Hill both of these species are critically endangered and now persist in single figures. The decline of these species is a result of overzealous Victorian plant collectors, historical quarrying activities, and invasive species. As part of the quarry restoration plan we were commissioned by Hanson UK to collect seeds of these two nationally rare plants and grow them on as part of a reintroduction project. Once our cultivated plants had reached a sufficient size we introduced them to a carefully selected part of the old quarry. The project is currently ongoing but initial indications are that the new populations we have foundered have successfully established.
Perennial Knawel & Upright Clover
Stanner Rocks National Nature Reserve, Radnorshire
Stanner Rocks is another famous site for rare plants including the Perennial Knawel Scleranthus perennis ssp perennis that is found nowhere else in the British Isles and Upright Clover Trifolium strictum that is only found elsewhere on the Lizard Peninsula in Cornwall. At Stanner Rocks both these species are restricted to a tiny spur of rock but were probably more widespread before quarrying activities in the nineteenth century. Perennial Knawel numbers fluctuate with approximately fifty plants each year. Upright Clover is critically endangered with just one or two plants appearing each year and occasionally none at all. We were commissioned under licence by Natural Resources Wales to collect seeds and cuttings from the wild plants and grow them on to produce large numbers of seeds for translocation to a carefully selected location on a different part of the reserve. We planted out Perennial Knawel seeds ten years ago, the new population has gradually increased in size and now supports over one thousand plants. The Upright Clover seeds were planted out seven years ago, the new population now supports between fifty and one hundred plants each year and represents a very significant percentage of the entire British population.
The Powys Rare Plants Project
Restoring rare plant populations in Mid Wales
With funding from the Welsh Government and in collaboration with the three Mid Wales Wildlife Trusts we are currently working on an ambitious species recovery project. The project is targeting a dozen species that have declined in Powys or have been lost altogether. This project will see the establishment of new populations of Spreading Bellflower Campanula patula, Maiden Pink Dianthus deltoides, Globeflower Trollius europaeus and Wood Bitter-vetch Vicia orobus and the resurrection of extinct species including Heath Cudweed Omalotheca sylvatica and Annual Knawel Scleranthus annuus.
This Red Data Book biennial is primarily a plant of well-drained soils associated with waste ground, tracksides and dry grasslands. Most of its existing sites are on the South Downs in Sussex. At a site near Brighton planning permission was recently granted for a new residential development that would result in the partial loss of a Red Star-thistle population. As part of a mitigation package a translocation exercise is planned to establish a new population of Red Star-thistle close by. As an insurance policy, in case the translocation fails or the plant disappears from the retained parts of the site, we were commissioned to retain a backup population in our rare plants nursery. In addition, seeds were also sent to Kew’s Millennium Seed Bank for long term storage.
This nationally scarce plant of unimproved hay meadows and rocky banks is restricted to the western half of Britain. We were commissioned by Radnorshire Wildlife Trust to grow on seeds of Wood Bitter-vetch for a species recovery project at the Trust’s flagship reserve Gilfach. At Gilfach Wood Bitter-vetch is restricted to an old railway cutting and rock ledges along the River Marteg. However, it would once have been a component of the nearby unimproved hay meadows but was lost in these areas through inappropriate management prior to the Trust taking ownership. Poor powers of seed dispersal have prevented re-colonisation of the hay meadows despite over twenty five years of favourable management. Following consultation with the Trust’s scientific committee and Natural Resources Wales it was decided to give the Wood Bitter-vetch a helping hand. We were commissioned to grow on seeds from the existing population and plant out the subsequent plants. The project is ongoing and the first plants were planted out into the hay meadows last year. All these plants are growing well and have successfully established.
Port Meadow, Oxfordshire
Port Meadow is famous for the globally rare Creeping Marshwort Helosciadium repens. An interesting looking Marshwort was collected from Port meadow by our staff in 2001. This material was grown on and held in cultivation. By special request plants were recently passed to researchers at Leicester University who were studying the Helosciadium genus. Through genetic analysis the researchers were able to confirm suspicions that our plant was a hybrid between Creeping Marshwort and Fool’s Watercress Helosciadium nodiflorum, the first confirmed record of this hybrid anywhere in the world. This research has implications on site management for Creeping Marshwort and future reintroduction projects. It has also illustrated the difficulty in identifying some Helosciadium hybrids in the wild where they seldom reach a size that allows positive identification.
Whilst not as rare as many of the other plants that we hold in cultivation the Globeflower is nevertheless a rapidly declining species and is a Biodiversity Action Plan (BAP) priority species in some parts of the country. We have successfully reintroduced this beautiful plant into a marshy grassland in Mid Wales which had lost its Globeflowers as a result of inappropriate management. The new population was foundered from seeds collected from a nearby population that was under threat from erosion of its riverbank habitat. We got there just in time, shortly after we collected seeds the last remaining wild plants were washed away in a flood.
Spreading Bellflower is one of our most threatened plants. Our material is from a site in Shropshire where the Spreading Bellflower is in steep decline. We have supplied material from our collection to researchers undertaking DNA analysis that hopes to shed more light on the reasons for its rapid decline.
Wales was the first country in the world to DNA bar code its entire native flora. We were able to assist in this ground breaking project by providing material from our collection. This included the very rare Radnor Lily Gagea bohemica that we hold in cultivation under special licence.
We have donated pressed material of some of our rarest plants to national herbarium collections. Cultivated material that is carefully preserved allows a perfect representation of key characters. Wild collected material is often limited by the time of year it was collected and may lack flowers, seeds and other important features.
Some of our rare plants have found their way into Kew’s Millennium Seed Bank at Wakehurst Place.