''Senecio cambrensis'' (Welsh groundsel or Welsh ragwort) is a

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

of the family

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...

and currently known only from

North Wales , area_land_km2 = 6,172 , postal_code_type = Postcode , postal_code = LL, CH, SY , image_map1 = Wales North Wales locator map.svg , map_caption1 = Six principal areas of Wales common ...

. It is a recently evolved plant that arose as a result of

hybridization Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...

between two related species.

Discovery

It was first noticed in 1948 by Horace E. Green at

Ffrith Ffrith is a small village in the community of Llanfynydd in Flintshire, north-east Wales. Name The name Ffrith (the Welsh double "f" is pronounced simply as "f") reflects a spelling and pronunciation particular to Flintshire: it is derived from ...

Flintshire , settlement_type = County , image_skyline = , image_alt = , image_caption = , image_flag = , image_shield = Arms of Flint ...

, north-east

Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...

The species was described in 1955 by Effie M. Rosser of

Manchester Museum Manchester Museum is a museum displaying works of archaeology, anthropology and natural history and is owned by the University of Manchester, in England. Sited on Oxford Road ( A34) at the heart of the university's group of neo-Gothic buildings, ...

using material from the site. It later turned up at a number of sites across the north-east of Wales including

Chirk Chirk ( cy, Y Waun) is a town and community in Wrexham County Borough, Wales, south of Wrexham, between it and Oswestry. At the 2011 census, it had a population of 4,468. Historically in the traditional county of Denbighshire, and later Clwy ...

Brymbo Brymbo is a village and Community (Wales), community in Wrexham County Borough, Wales. It lies in the hilly country to the west of Wrexham city, largely surrounded by farmland. At the United Kingdom Census 2001, 2001 Census, the population of t ...

, Queensferry and

Colwyn Bay Colwyn Bay ( cy, Bae Colwyn) is a town, community and seaside resort in Conwy County Borough on the north coast of Wales overlooking the Irish Sea. It lies within the historic county of Denbighshire. Eight neighbouring communities are incorpo ...

and a

herbarium A herbarium (plural: herbaria) is a collection of preserved plant specimens and associated data used for scientific study. The specimens may be whole plants or plant parts; these will usually be in dried form mounted on a sheet of paper (called ...

specimen was discovered that had been collected at Brynteg in 1925.

Origin

Welsh groundsel is an

allopolyploid Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains ...

, a plant that contains sets of

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

s originating from two different species. Its ancestor was ''Senecio × baxteri'', an infertile hybrid that can arise spontaneously when the closely related groundsel (''

Senecio vulgaris ''Senecio vulgaris'', often known by the common names groundsel and old-man-in-the-spring, is a flowering plant in the family Asteraceae. It is an annual herb, native to Europe and widely naturalised as a ruderal species in suitable disturbed hab ...

'') and Oxford ragwort ('' Senecio squalidus'') grow alongside each other. Sometime in the early 20th century, an accidental doubling of the number of chromosomes in an ''S. × baxteri'' plant led to the formation of a new fertile species, Welsh groundsel. Groundsel has a chromosome number 2n = 40; Oxford ragwort 2n = 20; and Welsh groundsel 2n = 60.

Identification

It is intermediate in appearance between the parents. It is an erect

annual plant An annual plant is a plant that completes its life cycle, from germination to the production of seeds, within one growing season, and then dies. The length of growing seasons and period in which they take place vary according to geographical ...

that reaches a height of 30 (sometimes 50) cm. The stem and leaves have few or no hairs. The leaves are deeply lobed. The lower leaves have stalks, whereas the upper leaves are attached directly to the stem. The

flower heads A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

are cylindrical and usually have 8 to 15 yellow

ray floret The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

s ("petals") although some are rayless. The ray florets vary in length but are most commonly 4 to 7 mm long. The

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...

grains are 30 to 36

micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

s across and usually have 4 pores.

Distribution

Outside Wales, it was erroneously reported from

Shropshire Shropshire (; alternatively Salop; abbreviated in print only as Shrops; demonym Salopian ) is a landlocked historic county in the West Midlands region of England. It is bordered by Wales to the west and the English counties of Cheshire to th ...

in 1970 and introduced into a school garden in

Wolverhampton Wolverhampton () is a city, metropolitan borough and administrative centre in the West Midlands, England. The population size has increased by 5.7%, from around 249,500 in 2011 to 263,700 in 2021. People from the city are called "Wulfrunian ...

in the 1990s, where it did not survive. However, in 1982, Welsh groundsel was discovered at several sites around

Edinburgh Edinburgh ( ; gd, Dùn Èideann ) is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. Historically part of the county of Midlothian (interchangeably Edinburghshire before 1921), it is located in Lothian ...

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...

. This population arose independently from the Welsh population; it is believed to date from at least 1974 but now appears to have disappeared with no records since 1993.

Habitat

Typical habitats of the species include waste ground, roadsides and cracks in walls and pavements. The population fluctuates considerably from year to year, but overall appears to be declining. Threats include spraying to kill weeds, road widening, and infection by the rust ''Puccinia lagenophorae'' Cooke, 1884, which can decimate large stands.

References

{{Taxonbar, from=Q5436615 cambrensis Endemic flora of Wales Speciation events Near threatened plants