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.


Apium (now recently reclassified as Helosciadium)

We have a range of Apium species and hybrids in cultivation including Creeping Marshwort Apium repens from Port meadow in Oxfordshire as well as F1 and F2 Creeping Marshwort hybrids with Fool’s Watercress Apium nodiflorum, also from Port Meadow. These hybrids have yet to be recorded anywhere else in the world. We also have Apium x moorei, the rare endemic hybrid between Lesser Marshwort Apium 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 restricted to Chippenham Fen in Cambridgeshire. We also have two very rare foreign Marshworts in our collection; Balearic Marshwort Apium bermejoi that is endemic to Minorca and its even rarer naturally occurring hybrid with Fool’s Watercress. 


Interrupted Brome

Bromus interruptus

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.



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.

Corn Cleavers

Gallium tricornutum

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.


Fringed Rupturewort

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 a number 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. 


Irish Saxifrage

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.

Welsh Groundsel

Senecio cambrensis

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-five 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.

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