OXFORD RAGWORT

Senecio squalidus

Daisy & Dandelion Family [Asteraceae]  

Flowers:
month8apr month8april month8may month8jun month8june month8jul month8july month8aug month8sep month8sept month8oct month8nov

Pappus: pappusZpossible (white, simple)
pappus8aug pappus8sep pappus8sept pappus8oct pappus8nov

status
statusZneophyte
 
flower
flower8yellow
 
morph
morph8actino
 
petals
petalsZMany
12-15
petals
petalsZ0
rarely
stem
stem8round
 
stem
stem8ribbed
 
toxicity
toxicityZmedium
 
sex
sexZbisexual
 

17th April 2014, Bridgewater Canal, Ordsall, Manchester. Photo: © RWD
It grows to 50cm high and is a perennial.


17th April 2014, Bridgewater Canal, Ordsall, Manchester. Photo: © RWD
There are between 12 and 15 ray florets on each floret. Only rarely are there no ray florets, just disc florets in the middle.


Photo: © RWD
The leaf shape can vary considerably, here they are almost near normal.


2nd Aug 2009, ex-Windsor High School, Salford, Lancs. Photo: © RWD
A short to medium well branched plant with satin hairless pinnately lobed (or sometimes undivided) leaves with largish showy yellow flowers. Leaves less intricately divided than those of Common Ragwort. Leaves greener than those of the slightly greyer Common Ragwort.

The leaves here, being linear near the summit and deeply pinnately lobed further down are even more 'normal' (but it does vary a lot).



29th Aug 2017, Manchester City Centre streets. Photo: © RWD
In this specimen the stems are ribbed. Again the leaves of this specimen differ slightly from others shown.


2nd Aug 2009, ex-Windsor High School, Salford, Lancs. Photo: © RWD
Un-opened flower buds have seemingly very narrow petals, but they are merely curled up.


2nd Aug 2009, ex-Windsor High School, Salford, Lancs. Photo: © RWD
The longer inner bracts are tipped black, as are the much shorter outer bracts.


21st May 2012, Southport, Sefton Coast. Photo: © RWD
When the ray florets have opened out, the long black-tipped bracts get deflected outwards (but the lower ones remain close to the lower part of the cups.


2nd Aug 2009, ex-Windsor High School, Salford, Lancs. Photo: © RWD
The short black-tipped bracts extend a little down the stem, reminiscent of those of Cat's-ear.


31st dec 2017, Castlefields, Manchester. Photo: © RWD
The petals (aka ligules) are 12 to 15 in number and between 6 to 10mm long on Oxford Ragwort. Here also showing the smaller disc florets in the centre.


2nd Aug 2009, ex-Windsor High School, Salford, Lancs. Photo: © RWD
The black-tipped bracts.


31st dec 2017, Castlefields, Manchester. Photo: © RWD
The tips of the both phyllaries at the top and the stem bracts wrapping around the lower parts have longish blackened tips.


21st May 2012, Southport, Sefton Coast. Photo: © RWD
Leaves alternate up the slightly ridged stem. Stem leaves which are down-turned at the edges (Unlike Common Ragwort where the lowest leaves have up-turned edges).


2nd Aug 2009, ex-Windsor High School, Salford, Lancs. Photo: © RWD
The lower leaves may be a little wider and less deeply divided. But the leaves of Oxford Ragwort do vary a lot anyway. These from the ex-Windsor High School have been assessed by experts and they agree that it is indeed Oxford Ragwort.


29th Aug 2017, Manchester City Centre streets. Photo: © RWD
Apart from the strange green coloration, these leaves are more or less the same shape as shown in the book, but the shape of Oxford Ragwort leaves is very variable, due to it's importation into the UK being from hybrids occurring in Southern Europe. [photo colour temperature dicky]


29th Aug 2017, Manchester City Centre streets. Photo: © RWD
As above photo, but a close-up. [photo colour temperature dicky]


21st May 2012, Southport, Sefton Coast. Photo: © RWD
The pappus together with a few disc florets yet to turn to seed and parachute hairs.


21st May 2012, Southport, Sefton Coast. Photo: © RWD
White pappus hairs attached directly to the fawn-coloured seeds. Black-tipped bracts in lower part of image.


21st May 2012, Southport, Sefton Coast. Photo: © RWD
Seeds long, slightly barrel-shaped and with darker ridges. Some seeds have already flown the best leaving what looks like an un-spherical golf-ball complete with aerodynamic dimples.




ANOTHER DIFFERING LEAF SHAPE

These specimens have also been confirmed as being one of Oxford Ragworts many forms

15th July 2019, waste ground, nr Sowerby Bridge Rly Stn. Photo: © RWD
There were quite a few of these forms of Oxford Ragwort near the railway station.


15th July 2019, waste ground, nr Sowerby Bridge Rly Stn. Photo: © RWD
The leaves are narrower but still have many irregular lobes.


15th July 2019, waste ground, nr Sowerby Bridge Rly Stn. Photo: © RWD
Another difference is in the length to width ratio of the cup formed by the phyllaries below the inflorescence - which is long and narrow. Oh, and some of the disc florets are beneath the petals!


15th July 2019, waste ground, nr Sowerby Bridge Rly Stn. Photo: © RWD
The disc florets from above.


15th July 2019, waste ground, nr Sowerby Bridge Rly Stn. Photo: © RWD
The leaves again, which are, rather than being sinly on the stem, are remarkably in whorls around the stem. Are we sure these specimens are of Oxford Ragwort?


Not to be semantically confused with : Perennial Ragweed (Ambrosia psilostachya) or Ragweed (Ambrosia artemisiifolia) but these totally lack any ray florets [more members of the Dandelion & Daisy Family (Asteraceae)]. Nor with Ragged-Robin (Silene flos-cuculi) [a member of the Campion family (Caryophyllacaea)].

Hybridizes with :

  • Sticky Groundsel (Senecio viscosus) to produce Senecio × subnebrodensis
  • Groundsel (Senecio vulgaris) to produce Senecio × baxteri

Some similarities to : A few other Ragworts.

Gets its name from where it was first grown in the UK, Oxford Botanical Gardens, from which it escaped in 1794 and has been slowly spreading around the UK ever since.

Oxford Ragwort (and other Ragworts) contain poisonous Pyrrolizidine Alkaloids that are released both in the pollen and in the sap. Because it is a controlled weed, and landowners are obliged to dig it up and remove it from their land depending upon the risk it poses to animals and humans (although, strangely, Councils often fail to do their duty in this regard, and instead set a bad example). Those most at risk of poisoning are those weeding the plant, or during a hot spell in Summer when a lot of pollen may be released from a large infestation. Direct skin contact with the sap should be avoided, thick rubber gloves should be worn by those digging up the plant. The toxins are mostly concentrated in the pollen, with progressively decreasing concentrations within, respectively, the leaves, stems and then the roots. The toxins have a cumulative effect in the body, building up in the body as exposure increases until they reach critical levels when symptoms of serious and irreversible liver damage leading to liver failure occur. It is fast spreading along motorways, for each plant produces thousands of parachuted seeds that waft far and wide on the slightest breeze.

Horses and other grazing animals are at most risk of acute poisoning by Ragwort not only by directly eating the plant, but also if it gets mixed in with hay or bedding. However, they prefer not to eat it, and will only eat it if other grazing plants are in short supply. The toxic Pyrrolizidine Alkaloids are transferred into the milk of for example cows who eat the plants, and then into those who drink the milk. Similar transfer can occur into honey when bees visit plants containing these alkaloids, which can include a whole raft of species but mostly plants from the Borage Family and the Daisy Family (subgroup Senecioneae), and a few from the Pea and Orchid Families. Ragwort should not be burnt, as the emitted toxins can be inhaled by humans.

But it should be remembered that 'the law is an ass' and generally made by pressure groups mainly from the landed gentry. Eradication of all Ragwort species is totally impossible. Common Ragwort (not the subject of this page) is a native of the UK and has been here a very long time. [Oxford Ragwort is not native]. All Ragworts spread by releasing parachuted hairs carrying one seed on to the wind - thousands of them per plant. Even if eradication were feasible, it would cost far more than those landed gentry who pushed for eradication laws like this to ever fund, even with their stashed-away £billions upon which they have probably paid very little, if any, income tax! Cattle and horses wont normally eat Ragworts if there is grass in the field to eat. Horse owners and farmers should ensure that any fields used by animals have a plentiful supply of grass or hay to eat. But if their animals are on a diet in a field bereft of all nutrition, then the landed gentry will have to dig up any ragworts themselves :-)

Several insects specialise on plants containing Pyrrolizidine Alkaloids, which they accumulate and use as defence mechanisms. The Cinnabar Moth on Ragwort is one such example.

SENECIONINE

Senecionine (aka Aureine and Squalidine) is a pyrrolizidine alkaloid which is hepatotoxic, damaging the liver on ingestion, and found within Tansy and also in species of Senecio [in the Daisy Family] (which includes Ragworts, Groundsels) and species of Crotalaria (a member of the Pea Family) which grows in the tropics. Senecionine has uses in the biological laboratory.


USE BY BUTTERFLIES
LAYS EGGS ON CATERPILLAR CHRYSALIS BUTTERFLY
Small Pearl-bordered Fritillary



  Senecio squalidus  ⇐ Global Aspect ⇒ Asteraceae  

Distribution
 family8Compositae family8Daisy family8Dandelion family8Asteraceae
 BSBI maps
genus8Senecio
Senecio
(Ragworts)

OXFORD RAGWORT

Senecio squalidus

Daisy & Dandelion Family [Asteraceae]  

WildFlowerFinder Homepage