''Senecio cambrensis'', the Welsh groundsel or Welsh ragwort, is a

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

of the family

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

. It is

endemic Endemism is the state of a species being found only 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 foun ...

Great Britain Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European ...

and currently known only from

North Wales North Wales ( ) is a Regions of Wales, region of Wales, encompassing its northernmost areas. It borders mid Wales to the south, England to the east, and the Irish Sea to the north and west. The area is highly mountainous and rural, with Snowdon ...

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

Flintshire Flintshire () is a county in the north-east of Wales. It borders the Irish Sea to the north, the Dee Estuary to the north-east, the English county of Cheshire to the east, Wrexham County Borough to the south, and Denbighshire to the west. ...

, north-east

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

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 Wilmslow Road, Oxford Road (A34 road, A34) at the heart of the university's group ...

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

Chirk Chirk () is a town and Community (Wales), 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 historic counties of Wales, traditional coun ...

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

, Queensferry and

Colwyn Bay Colwyn Bay () is a town, Community (Wales), community and seaside resort in Conwy County Borough on the north coast of Wales overlooking the Irish Sea. It lies within the historic counties of Wales, historic county boundaries of Denbighshire (h ...

and a

herbarium A herbarium (plural: herbaria) is a collection of preserved plant biological specimen, 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 sh ...

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 two paired sets of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two complete sets of chromosomes, one fro ...

, a plant that contains sets of

chromosome A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most import ...

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 plant, annual herbaceous plant, herb, native to the Palaearctic and widely naturalised as a ...

'') and Oxford ragwort (''

Senecio squalidus ''Senecio squalidus'', known as Oxford ragwort, is a flowering plant in the daisy family Asteraceae. It is a yellow-flowered herbaceous plant, native to mountainous, rocky or volcanic areas, that has managed to find other homes on man-made and n ...

'') 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. Globally, 6% of all plant species and 15% of herbaceous plants (excluding trees and shrubs) are ...

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 (; : pseudanthia) 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, composite flowers ...

are cylindrical and usually have 8 to 15 yellow

ray floret Asteraceae () is a large family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the order Asterales. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger fam ...

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 most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

grains are 30 to 36

micrometre The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...

s across and usually have 4 pores.

Distribution

Outside Wales, it was erroneously reported from

Shropshire Shropshire (; abbreviated SalopAlso used officially as the name of the county from 1974–1980. The demonym for inhabitants of the county "Salopian" derives from this name.) is a Ceremonial counties of England, ceremonial county in the West M ...

in 1970 and introduced into a school garden in

Wolverhampton Wolverhampton ( ) is a city and metropolitan borough in the West Midlands (county), West Midlands of England. Located around 12 miles (20 km) north of Birmingham, it forms the northwestern part of the West Midlands conurbation, with the towns of ...

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

Edinburgh Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh ...

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

. 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