Ragworts Senecio species
 
Family – Asteraceae, Daisy family
Annual to perennial up to 50cm
Flowering – May to December
Soils - all soils
Sun  -  full sun
 
There are about 9 species of the genus Senecio or Ragwort in Britain and Ireland.  Three are relevant to gardens where they can be common gatecrashers. We will describe two native species and one newcomer.
 
•  Common ragwort Senecio jacobaea
•  Oxford ragwort Senecio squalidus
•  Groundsel Senecio vulgaris
 
 
 
Common ragwort Senecio jacobaea (sometimes called Jacobaea vulgaris)
This native plant was first noted by Gerard in 15971. who wrote “Lande Ragwoort growth every where in untilled pastures and fields, which are somewhat moist especially”. It rejoices in dozens of local names ranging from yellow weed or yellow top to mugger, ragged jack, mares’ fart and stinking Billy. Unofficially, it is the national flower of the Isle of Man, (named “cushag” in Manx gaelic) so called it is believed, “by a sarcastic Victorian Governor-General who said it must be, there is so much of it in the fields”.2.
 
Common ragwort is one of seven (mostly native) species classed as a noxious weed, meaning it is considered able to cause harm to agriculture.  Landowners are responsible for preventing their spread onto adjoining land,3. which in the case of common ragwort means preventing it from setting seed, which can be carried for miles on the wind. There is a useful Government code of practice on this species including information about its control.4.   The main problem is the plant’s toxicity, especially to horses and other equines, especially if dried and accidentally incorporated into fodder.
 
Fortunately, common ragwort isn’t a major problem in gardens, but it can appear in lawns and flower beds where the soil is disturbed. It forms a rosette in its first year and flowers as a biennial in its second.  The RHS has a useful profile on the “weed”.5. Common ragwort is visited by pollinating flies, and  supports over 90 insect species including the small copper butterfly Lycaena phlaeas and many moths, especially the cinnabar moth Tyria jacobaeae.6.  It is a pity ragwort is such a hated nuisance because it is quite striking in appearance and supports so many species.
 
Above, Cinnabar moth caterpillars on common ragwort and an adult moth
 
Oxford ragwort Senecio squalidus
As with other Senecio species, Oxford ragwort is valuable nectar plant for bees and hoverflies. It is a larval food plant10. for the hoverfly Cheilosia bergenstammi  and the Tephrid fly Trypeta zoe whose larvae mine the leaves. The cinnabar moth Tyria jacobaeae which has a preference for common ragwort occasionally lays its eggs on Oxford ragwort. In addition, the seeds are taken by birds including goldfinches.11.
 
For its colour and exceptionally long flowering season on an otherwise inhospitable patch of front garden it is welcomed, even encouraged, along with prickly ox-tongue Helminthotheca echiodes and perennial  sow-thistle Sonchus arvensis.
 
 
Groundsel Senecio vulgaris
 
 
Groundsel is a native plant which has followed people around the world and is now common in many countries. It is an annual species, smaller than common or Oxford ragwort, with small almost stalk-less heads of flower.  It seeds prolifically and constantly appears seeded into cultivated ground such as vegetable patches and flower borders.
 
Groundsel was first described by William Turner in 1538.12.  It has a large variety of local names including canaryweed, chckenweed and (confusingly) chickweed (usually given to Stellaria media), lady’s finger and little lie-a-bed.13.  It was considered a good food for chickens, rabbits and cage birds. Groundsel is less toxic than the ragworts, and has been used as a cure for constipation, but is not recommended in modern usage because of cumulative liver toxicity.
 
Groundsel supports a very large number of larval insects, especially moths, including the cinnabar Tyria jacobaeae, the scarlet tiger moth Callimorpha dominula, and the wood tiger Parasemia plantaginis.14.
 
 
References
 
1.  Pearman, D. (2017). The Discovery of the Native Flora of Britain and Ireland, A compilation of the first records for 1670 species and aggregates, covering Great Britain, Ireland, The Channel Isles and the Isle of Man. Botanical Society of Britain & Ireland.p 369
 
2. Vickery, R. (2019). Vickery’s Folk Flora, An A to Z of the Folklore and Uses of British and Irish Plants. Weidenfeld & Nicolson. London. pp 555-560
 
3. https://www.nibusinessinfo.co.uk/content/your-legal-responsibilities-invasive-plants-and-noxious-weeds
 
4. Code of practice in control of ragwort 
 
5. Ragwort profile RHS https://www.rhs.org.uk/advice/profile?pid=299
 
6. Biological Record Centre database  
 
7. Wikipedia article on Oxford Ragwort
 
8. Mabey, R. 2010. Weeds. Profile Books, London.  p 139                                                                                     
 
9. Hanbury, J.F. and Marshall, E.S. 1999. Flora of Kent. Frederick Hanbury. London. p 202 (George Gulliver)   
 
10. Biological Record Centre database 
 
11. Owen, J. 2010. Wildlife of a garden – A thirty-year study. RHS. p 194                                                                                                                                                       
12. Pearman, D. (2017). The Discovery of the Native Flora of Britain and Ireland, A compilation of the first records for 1670 species and aggregates, covering Great Britain, Ireland, The Channel Isles and the Isle of Man. Botanical Society of Britain & Ireland. p375
 
13. Vickery, R. (2019). Vickery’s Folk Flora, An A to Z of the Folklore and Uses of British and Irish Plants. Weidenfeld & Nicolson. London. p320.
 
14. Biological Record Centre database
 
 
Page written by Caroline Ware.  Extended and compiled by Steve Head
 
 
Ragworts Senecio species
 
Family – Asteraceae, Daisy family
Annual to perennial up to 50cm
Flowering – May to December
Soils - all soils
Sun  -  full sun
 
There are about 9 species of the genus Senecio or Ragwort in Britain and Ireland.  Three are relevant to gardens where they can be common gatecrashers. We will describe two native species and one newcomer.
 
•  Common ragwort Senecio jacobaea
•  Oxford ragwort Senecio squalidus
•  Groundsel Senecio vulgaris
 
Common ragwort Senecio jacobaea (sometimes called Jacobaea vulgaris)
This native plant was first noted by Gerard in 15971. who wrote “Lande Ragwoort growth every where in untilled pastures and fields, which are somewhat moist especially”. It rejoices in dozens of local names ranging from yellow weed or yellow top to mugger, ragged jack, mares’ fart and stinking Billy. Unofficially, it is the national flower of the Isle of Man, (named “cushag” in Manx gaelic) so called it is believed, “by a sarcastic Victorian Governor-General who said it must be, there is so much of it in the fields”.2.
 
Common ragwort is one of seven (mostly native) species classed as a noxious weed, meaning it is considered able to cause harm to agriculture.  Landowners are responsible for preventing their spread onto adjoining land,3. which in the case of common ragwort means preventing it from setting seed, which can be carried for miles on the wind. There is a useful Government code of practice on this species including information about its control.4.   The main problem is the plant’s toxicity, especially to horses and other equines, especially if dried and accidentally incorporated into fodder.
 
Fortunately, common ragwort isn’t a major problem in gardens, but it can appear in lawns and flower beds where the soil is disturbed. It forms a rosette in its first year and flowers as a biennial in its second.  The RHS has a useful profile on the “weed”.5. Common ragwort is visited by pollinating flies, and  supports over 90 insect species including the small copper butterfly Lycaena phlaeas and many moths, especially the cinnabar moth Tyria jacobaeae.6.  It is a pity ragwort is such a hated nuisance because it is quite striking in appearance and supports so many species.
 
Above, Cinnabar moth caterpillars on common ragwort and an adult moth
 
Oxford ragwort Senecio squalidus
Groundsel is a native plant which has followed people around the world and is now common in many countries. It is an annual species, smaller than common or Oxford Ragwort, with small almost stalk-less heads of flower.  It seeds prolifically and constantly appears seeded into cultivated ground such as vegetable patches and flower borders.
 
Groundsel was first described by William Turner in 1538.12.  It has a large variety of local names including canaryweed, chckenweed and (confusingly) chickweed (usually given to Stellaria media), lady’s finger and little lie-a-bed.13.  It was considered a good food for chickens, rabbits and cage birds. Groundsel is less toxic than the ragworts, and has been used as a cure for constipation, but is not recommended in modern usage because of cumulative liver toxicity.
 
Groundsel supports a very large number of larval insects, especially moths, including the cinnabar Tyria jacobaeae, the scarlet tiger moth Callimorpha dominula, and the wood tiger Parasemia plantaginis.14.
 
 
References
 
1.  Pearman, D. (2017). The Discovery of the Native Flora of Britain and Ireland, A compilation of the first records for 1670 species and aggregates, covering Great Britain, Ireland, The Channel Isles and the Isle of Man. Botanical Society of Britain & Ireland.p 369
 
2. Vickery, R. (2019). Vickery’s Folk Flora, An A to Z of the Folklore and Uses of British and Irish Plants. Weidenfeld & Nicolson. London. pp 555-560
 
3. https://www.nibusinessinfo.co.uk/content/your-legal-responsibilities-invasive-plants-and-noxious-weeds
 
4. Code of practice in control of ragwort 
 
5. Ragwort profile RHS https://www.rhs.org.uk/advice/profile?pid=299
 
6. Biological Record Centre database  
 
7. Wikipedia article on Oxford Ragwort
 
8. Mabey, R. 2010. Weeds. Profile Books, London.  p 139                                                                                 
9. Hanbury, J.F. and Marshall, E.S. 1999. Flora of Kent. Frederick Hanbury. London. p 202 (George Gulliver)   
 
10. Biological Record Centre database 
 
11. Owen, J. 2010. Wildlife of a garden – A thirty-year study. RHS. p 194                                                                                                                             12. Pearman, D. (2017). The Discovery of the Native Flora of Britain and Ireland, A compilation of the first records for 1670 species and aggregates, covering Great Britain, Ireland, The Channel Isles and the Isle of Man. Botanical Society of Britain & Ireland. p375
 
13. Vickery, R. (2019). Vickery’s Folk Flora, An A to Z of the Folklore and Uses of British and Irish Plants. Weidenfeld & Nicolson. London. p320.
 
14. Biological Record Centre database
 
 
Page written by Caroline Ware.  Extended and compiled by Steve Head
 
 
This plant originated as a natural hybrid between two Mediterranean species Senecio aethnensis and Senecio chrysanthemifolius, growing on Mount Etna in Sicily.7. It was one of the earliest plants established at the Oxford University Botanic Garden by its first curator Jacob Bobart about 1690.  By 1794 the botanist Joseph Banks noted that it had escaped and was growing all over the stone work of Oxford.  From Oxford railway station it spread8. to urban areas throughout the rest of the country along the railway lines, aided by the slipstream of the trains, and the familiar habitat of well-drained crushed stone ballast – similar to its native surface on Mount Etna.
 
Interestingly, nearly a century later Oxford ragwort was still a novelty in Kent, so much so that it was picked by collectors, as observed by a contributor to the 1875 Flora of Kent: ‘This species grows on the walls at Canterbury, probably an importation; now so sparingly, owing to the ravages of collectors, as not likely to invite them any more. It is still very abundant in certain places within 2 miles of Canterbury, where I hope it may remain safe, especially as it is likely to be well protected.’9.  It has no need of protection today, being abundant in urban areas on wasteland,  on walls and waysides throughout Britain, and still spreading, with the aid of railways and motorways.  It is just as toxic as common ragwort, but less of a problem as it does not invade fields and get eaten by horses.
Oxford ragwort is an exuberant wild flower providing colour in pockets of paving, railway sidings and stations, and in and around urban streets and gardens. It is an annual to short-lived perennial and has pinnately lobed leaves, which may vary slightly in shape, and yellow ‘daisy’ flowers.
 
Left: Oxford ragwort with Allium sphaerocephalon in a Kent gardene
 
Oxford ragwort is easily distinguished from common ragwort when in flower, because it has loose, spreading flower heads, while common ragwort’s flowers are densely packed in tight umbel-like corymbs.  The leaves of common ragwort are usually darker and more glossy and tough than those of Oxford Ragwort.
Oxford ragwort is an exuberant wild flower providing colour in pockets of paving, railway sidings and stations, and in and around urban streets and gardens. It is an annual to short-lived perennial and has pinnately lobed leaves, which may vary slightly in shape, and yellow ‘daisy’ flowers.
 
Left: Oxford ragwort with Allium sphaerocephalon in a Kent gardene
 
Oxford ragwort is easily distinguished from common ragwort when in flower, because it has loose, spreading flower heads, while common ragwort’s flowers are densely packed in tight umbel-like corymbs.  The leaves of common ragwort are usually darker and more glossy and tough than those of Oxford Ragwort.
This plant originated as a natural hybrid between two Mediterranean species Senecio aethnensis and Senecio chrysanthemifolius, growing on Mount Etna in Sicily.7. It was one of the earliest plants established at the Oxford University Botanic Garden by its first curator Jacob Bobart about 1690.  By 1794 the botanist Joseph Banks noted that it had escaped and was growing all over the stone work of Oxford.  From Oxford railway station it spread8. to urban areas throughout the rest of the country along the railway lines, aided by the slipstream of the trains, and the familiar habitat of well-drained crushed stone ballast – similar to its native surface on Mount Etna.
 
Interestingly, nearly a century later Oxford ragwort was still a novelty in Kent, so much so that it was picked by collectors, as observed by a contributor to the 1875 Flora of Kent: ‘This species grows on the walls at Canterbury, probably an importation; now so sparingly, owing to the ravages of collectors, as not likely to invite them any more. It is still very abundant in certain places within 2 miles of Canterbury, where I hope it may remain safe, especially as it is likely to be well protected.’9.  It has no need of protection today, being abundant in urban areas on wasteland,  on walls and waysides throughout Britain, and still spreading, with the aid of railways and motorways.  It is just as toxic as common ragwort, but less of a problem as it does not invade fields and get eaten by horses.
Oxford ragwort is easily distinguished from common ragwort when in flower, because it has loose, spreading flower heads, while common ragwort’s flowers are densely packed in tight umbel-like corymbs.  The leaves of common ragwort are usually darker and more glossy and tough than those of Oxford Ragwort.
 
As with other Senecio species, Oxford ragwort is valuable nectar plant for bees and hoverflies. It is a larval food plant10. for the hoverfly Cheilosia bergenstammi  and the Tephrid fly Trypeta zoe whose larvae mine the leaves. The cinnabar moth Tyria jacobaeae which has a preference for common ragwort occasionally lays its eggs on Oxford ragwort. In addition, the seeds are taken by birds including goldfinches.11.
 
For its colour and exceptionally long flowering season on an otherwise inhospitable patch of front garden it is welcomed, even encouraged, along with prickly ox-tongue Helminthotheca echiodes and perennial  sow-thistle Sonchus arvensis.
 
 
Groundsel Senecio vulgaris
 
 
Oxford ragwort is an exuberant wild flower providing colour in pockets of paving, railway sidings and stations, and in and around urban streets and gardens. It is an annual to short-lived perennial and has pinnately lobed leaves, which may vary slightly in shape, and yellow ‘daisy’ flowers.
 
Left: Oxford ragwort with Allium sphaerocephalon in a Kent garden
 
 
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