Criggion Quarry, Breidden Hill, Montgomeryshire
Rock Cinquefoil Potentilla rupestris & Sticky Catchfly Silene viscaria
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 with many of the introduced plants flowering in their first and second years.
Stanner Rocks National Nature Reserve, Radnorshire
Perennial Knawel Scleranthus perennis & Upright Clover Trifolium strictum
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 in 2010, ten years on and the new population has gradually increased in size and now supports over one thousand plants. The Upright Clover seeds were planted out in 2013, seven years on and 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 about to commence work 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, Globeflower Trollius europaeus and Large-flowered Hemp-nettle Galeopsis speciosa and the resurrection of extinct species including Heath Cudweed Omalotheca sylvatica, Corn Buttercup Ranunculus arvensis 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 currently ongoing; the seeds have germinated and the young plants are growing well in our nursery. It is anticipated that the plants will have grown on to a sufficient size to be planted out into the hay meadows in early 2021.
Port Meadow, Oxfordshire
Creeping Marshwort Helosciadium repens
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 research scientists 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 diagnostic features. In addition wild collected material may have been damaged by animals or extreme weather, and in the case of some annual species growing in harsh conditions, may be diminutive in size.
Some of our rare plants have found their way into Kew’s Millennium Seed Bank at Wakehurst Place.