Short description of Senecio squalidus, Oxford Ragwort

Oxford ragwort is an erect, straggling winter green herb that usually behaves as an annual or short-lived perennial. It is quite variable and a number of different subspecies and varieties have been described. It grows up to a metre high and flowers between March and December. Flowers are yellow and typically daisy-like, borne in loose clusters at shoot tips. Leaves are quite glossy and dark green and pinnately lobed. It closely resembles several other ragworts.

Impact summary: Senecio squalidus, Oxford Ragwort

It hybridises with two native ragworts and contains alkaloids, which are toxic to humans and animals.

Habitat summary: Senecio squalidus, Oxford Ragwort

Most frequently encountered in dry, open situations, especially in disturbed urban habitats such as railway banks, waste ground and crumbling walls.

Overview table

Environment	Terrestrial
Species status	Non-Native
Native range	Europe, Middle Europe, Southeastern Europe
Functional type	Land plant
Status in England	Non-Native
Status in Scotland	Non-Native
Status in Wales	Non-Native
Location of first record	v.c.21
Date of first record	1794

Origin

It is widespread from middle Europe including Austria, Germany and Switzerland south-eastwards into Italy, Greece, Romania, Bulgaria and a number of other countries. It is also native to New Brunswick and Nova Scotia in Canada.

First Record

It was first reported from the wild in Oxford in 1794.

Pathway and Method

It has long been thought that Oxford Ragwort was introduced from material collected from Mount Etna in Sicily, escaping over the wall and dispersing as seeds along the railway network. However, Harris (2002) concluded that the initial introduction was more likely via the Duchess of Beaufort’s garden at Badminton between 1700 and 1702, with a later transfer of material to Oxford by 1719. Recent research has found that Oxford Ragwort is actually of hybrid origin. Its parents are two sub-species of Oxford Ragwort, S. squalidus ssp. aethnensis and S. squalidus ssp. chrysanthemifolius which are both only found in Sicily.

Species Status

It is abundant and widespread across lowland GB, occurring in 1573 10km grid squares by 1999. It appears to have invaded slowly at first, but records of occurrences increased enormously in the second part of the twentieth century. However, between 1987 and 2004 the BSBI's Local Change project found that it declined by about 30%. In Europe it is naturalised in France, Belgium, Norway and Sweden and further afield, in California and the Falkland Islands.

Dispersal Mechanisms

Plants produce masses of plumed seeds which are supremely adapted to wind dispersal, and there are a number of accounts of the rapid spread of Oxford Ragwort from Oxford along the railway network in the air currents created by moving trains. More recently, vehicles moving along motorways have dispersed the plant over considerable distances in the same way.

Reproduction

Oxford Ragwort is capable of flowering between March and December and produces bisexual flowers of two kinds in compound inflorescences. Flowers are pollinated by a range of insects and are self-incompatible so must cross-pollinate with other plants. Every year from June onwards each plant is capable of producing approximately 10,000 hard, plumed seeds which need exposure to light to germinate well. Seeds germinate in spring and autumn and most plants flower within their first year of growth.

Known Predators/Herbivores

Oxford Ragwort is toxic to cattle, horses and goats and to a lesser extent, sheep. However, it is a food plant of various insects including the larvae of the Cinnabar moth Tyria jacobaeae and a number of gall flies. A number of rusts, powdery mildews and other fungi will also attack it.

Resistant Stages

None. Seeds are short-lived and do not persist for long in the soil. Plants tend to complete their life cycles within a few years at most.

Habitat Occupied in GB

It is very characteristic of dry, disturbed places including cultivated and waste ground, road verges, railway embankments, walls, pavement cracks and crumbling building mortar.

It is widespread and common in GB from a line south of the Great Glen, and is a frequent sight on waste and disturbed land in urban areas. It is mostly absent from upland areas including much of Wales and Scotland. It is quite rare in Ireland.

Environmental Impact

Contrary to some information sources, Oxford Ragwort rarely grows in established or perennial habitats e.g. grassland. However, it hybridises with the native Groundsel S. vulgaris and rarely, Sticky Groundsel S. viscosus and has given rise to several hybrids including Welsh Groundsel S. cambrensis.

Health and Social Impact

Like other ragwort species, the sap and pollen of Oxford Ragwort contains poisonous alkaloids which, when ingested or absorbed via the skin in sufficient quantities can cause liver damage to humans and animals.

Economic Impact

As it does not generally invade pasture where livestock are likely to come into contact with it Oxford Ragwort does not appear to have significant economic impacts.

Identification

Sell, P. & Murrell G. (2006) Flora of Great Britain and Ireland: Volume 4: Campanulaceae to Asteraceae, Cambridge University Press.

Stace, C.A. (2010) New flora of the British Isles, Third Edition, Cambridge University Press, Cambridge.

Biology, ecology, spread, vectors

Bond, W. & Davies G. (2007) The biology and non-chemical control of Oxford Ragwort (Senecio squalidus L.). Factsheet from HDRA website: www.gardenorganic.org.uk.

Braithwaite, M.E., Ellis, R.W. & Preston, C.D. (2006) Change in the British Flora 1987-2004. Botanical Society of the British Isles.

Harris, S.A. (2002) Introduction of Oxford Ragwort, Senecio squalidus L. (Asteraceae) to the United Kingdom. Watsonia, 24, 31-43.

Preston, C.D., Pearman, D.A. & Dines, T.D. (2002) New Atlas of the British and Irish Flora, Oxford University Press, Oxford.

DAISIE European Invasive Alien Species Gateway: www.europe-aliens.org

Global Invasive Species Database: www.issg.org

NBN Gateway: www.nbn.org.uk

Management and impact

Bond, W. & Davies G. (2007) The biology and non-chemical control of Oxford Ragwort (Senecio squalidus L.). Factsheet from HDRA website: www.gardenorganic.org.uk.

General

Braithwaite, M.E., Ellis, R.W. & Preston, C.D. (2006) Change in the British Flora 1987-2004. Botanical Society of the British Isles.