Extinct species and endemics
Some of the extinct species and endemics we hold in cultivation are showcased below and are listed in alphabetical order by scientific name.
The Interrupted Brome is an English endemic grass that became extinct in the wild in 1972. Fortunately it was saved from global extinction by Philip Morgans Smith who was secretly cultivating it in his garden. It has recently been introduced to experimental plots near Whittlesford in Cambridgeshire.
Isle of Man Cabbage
Coincya monensis ssp. monensis
This rare cabbage is endemic to Britain. It grows on sandy ground and cliffs close to the sea. It is found on the Isle of Man, the western coast of northern England and the estuary of the River Clyde.
Over the years we have cultivated all ten of the British fumitories. Two of these are endemic; Purple Ramping Fumitory Fumaria purpurea and Western Ramping Fumitory F. occidentalis that is restricted entirely to Cornwall and the Scilly Isles.
As a proper native species Corn Cleavers is now extinct but a small population is maintained at Rothamsted Experimental Station in Hertfordshire. Our material originates from Rothamsted.
Geranium purpureum ssp. forsteri
Little Robin is known from a number of different habitat types in southern England ranging from hedge banks and coastal cliffs to railway cuttings and roadside verges. Our material is from Hayling Island in Hampshire where it grows on coastal shingle. This rarer prostrate coastal variant is often referred to as ssp. forsteri and is an English endemic.
We have a range of Helosciadium species and hybrids in cultivation including Creeping Marshwort Helosciadium repens from Port meadow in Oxfordshire as well as F1 and F2 Creeping Marshwort hybrids with Fool’s Watercress Helosciadium nodiflorum, also from Port Meadow. These hybrids have yet to be recorded anywhere else in the world. We also have Helosciadium x moorei, the rare endemic hybrid between Lesser Marshwort Helosciadium inundatum and Fool’s Watercress. We are particularly lucky to have the endemic intergeneric hybrid between Lesser Water-parsnip Berula erecta and Fool’s Watercress that was described new to science in 2015 and is currently known from two British sites. We also have two very rare foreign Marshworts in our collection; Balearic Marshwort Helosciadium bermejoi that is endemic to Minorca and its even rarer naturally occurring hybrid with Fool’s Watercress.
Herniaria ciliolata ssp. ciliolata
An endemic subspecies found on the Lizard Peninsula in Cornwall.
The British Isles supports over four hundred species of Hawkweed many of which are endemic with extremely limited distributions. We have lots of Hawkweeds in cultivation including Snowdon Hawkweed Hieracium snowdoniense that was rediscovered in Snowdonia in 2002 after being considered extinct for almost fifty years. Three other Welsh endemics that we hold in cultivation include Cilau Hawkweed Hieracium cilense that is only found on the botanically rich cliffs of Craig y Cilau in Brecknock, the recently described Attenborough’s Hawkweed Hieracium attenboroughiana that is restricted a single rocky crag in the Brecon Beacons, and Llanwrtyd Hawkweed Hieracium subminutidens that is only known from a small number of rocky outcrops along the River Irfon.
Shetland Mouse-ear Hawkweed
Pilosella flagellaris ssp. bicapitata
Shetland Mouse-ear Hawkweed is endemic to Shetland where it is known from just three locations. Rare in the wild but quite invasive on our rockery.
Saxifagea rosacea ssp rosacea
As a native plant in the British Isles Irish Saxifrage is now only known from Ireland. However, it did once occur at Cwm Idwal in Snowdonia but became extinct here almost immediately after its discovery in 1962. Fortunately material from the original find was cultivated by an amateur botanist. Recent DNA analysis has confirmed that the Cwm Idwal Irish Saxifrage is distinct from its Irish counterparts and was a genuine native species at Cwm Idwal. Plants retained in cultivation will hopefully allow a future reintroduction to Cwm Idwal. Our material originates from the original Cwm Idwal collection in 1962.
Breckland Perennial Knawel
Scleranthus perennis ssp. prostratus
This prostrate form of Perennial Knawel is endemic to the Breck grasslands of Norfolk, Suffolk and Cambridge. It was first discovered in the seventeenth century by the great pioneering botanist John Ray. The largest population of this British endemic occurs at RAF Lakenheath where it is unwittingly protected by the American military who are stationed there. Polite gun wielding American soldiers usually see off any visiting botanists.
Welsh Groundsel is endemic to North Wales but was previously known from Scotland where it is now extinct. Its habitat is entirely artificial and comprises urban sites where there is suitable bare ground for seedling establishment. Such areas comprise waste ground, stone walls and the edges of roads and pavements. The Welsh Groundsel is one of our most threatened plants. This recently evolved species formed from a hybrid between Oxford ragwort Senecio squalidus and Common Groundsel Senecio vulgaris. In 1983 the Welsh population numbered 2226 individuals, in 2004 the population numbered 349 individuals, the most recent detailed survey undertaken in 2011 found just 168 plants. These patterns of decline mirror that of the Scottish population that declined rapidly until it became extinct in 1993. Lack of open ground, herbicide applications to roadside verges, and the winter salting of roads are the most likely reasons for its decline. As a wild plant Welsh Groundsel appears to be heading towards extinction and as such plants held in cultivation by us and other botanical institutions will become particularly important.
The British Isles supports at least thirty-eight species of Whitebeam that are found nowhere else in the world, many of these are incredibly rare with some species restricted to just a small handful of individuals. Our Sorbus arboretum currently supports seventeen of these endemic trees. The arboretum has been established over many years and many of the trees are now well established and flower most years. We are constantly adding to our Sorbus collection, most recently we added Motley’s Whitebeam Sorbus x motleyi that was donated by The National Botanic Garden of Wales, only two trees of this recently described hybrid are known in the wild. In 2014 a collecting trip to Breidden Hill allowed us to obtain seeds from the ‘type’ tree of Stirton’s Whitebeam Sorbus stirtoniana that is found nowhere else in the world, these seeds are now small saplings and were added to the arboretum in 2018.