Information

How to prevent the spread of ragwort: guidance

The guide offers advice to prevent and control the spread of ragwort where there is a threat to the health and welfare of animals.


Appendix 2: biology and identification

Introduction

1 Common ragwort (senecio jacobaea) is an erect plant usually 30-90cm high, but may exceed 100cm. The stems are tough and often tinged red near the base, but brighter green and branched above the middle. A basal rosette of leaves usually dies before flowering but the stem leaves persist. They are deeply dissected, with irregular, jagged-edged lobes. All the leaves are dark green and rather tough and may be sparsely hairy on the lower side. The inflorescence is a conspicuous, large, flat-topped head of densely packed yellow flowers with ray florets and disc florets, all of which are bright yellow. The seeds are borne singly and have a downy appendage making them readily dispersible. Once in the soil seeds can lie dormant for several years before germinating.

Biology

2 Common ragwort is normally biennial (rosette 1st year and flowering 2nd year). During its first year of growth it establishes a rosette of basal leaves and over winters in this way. During the second year the rosette sends up one or more leafy stem, up to one metre in height, which is unbranched and produces numerous flower heads at the top. The flower heads are carried in a large flat-topped cluster. Flowering usually occurs from June until late October after which the plant dies.

3 Common ragwort can also behave as perennial (flowering every year) after damage to the crown such as cutting, grazing, hoof damage, damage by machinery and following incomplete/ineffective hand pulling in dry weather. It can also remain in the rosette stage for several years under intensive cutting regimes such as may be practised on amenity grassland.

Distribution

4 Common ragwort is widespread throughout the UK and can be found on wasteland, development land, roadside verges, railway land, amenity land, conservation areas, set-aside, woodland and grazing land. Poor quality and poorly managed horse pastures are particularly susceptible to high densities of ragwort.

Habitat

5 Common ragwort can be found over a large range of soil types and climatic conditions, it can be characteristic of badly managed grasslands, where trampling breaks the sward, where patches of turf have died in drought or where there is over or under grazing. However, well-managed acid/calcareous grasslands may naturally contain ragwort. Disturbance to grass verges, embankments and woodland areas which leads to open soil are also favourable conditions for seedling establishment.

Other species of ragwort

6 Whilst only the more frequently found common ragwort is subject to the provisions of the Weeds Act, there are other members of the same native species family which can cause some identification problems. Marsh ragwort (senecio aquaticus) is locally abundant in wet areas of fields, ditch banks and marshes. hoary ragwort (senecio erucifolius) occurs mainly on roadsides, semi-natural meadows and field boundaries. Oxford ragwort (senecio squalidus) grows widely on roadsides, railway land, old walls and unmanaged land.

Marsh Ragwort

Oxford Ragwort

Horay Ragwort

marsh ragwort
senecio aquaticus

oxford ragwort
senecio squalidus

hoary ragwort
senecio erucifolius

Common ragwort

Common Ragwort

Common ragwort lookalike plants

Field fleawort

field fleawort
tephroseris integrifolia

Yellow Loosestrife

yellow loosestrife
lysimachis vulgaris

Tansy

tansy
tananetum vulgare

Goldenrod

goldenrod
solidago virgaurea

Fleabane

fleabane
pulicaria vulgaris

Agrimonies

agrimonies
agrimonia spp.

St. John's worts

St. John's worts
hypericum spp.

Mulleins

mulleins
verbascum spp.

Heath Groundsel

heath groundsel
sencio sylvaticus

Sow Thistles

sow thistles
Sonchus spp.

Hawkweeds

hawkweeds
hieracium spp.

Elecampane

elecampane
inula helenium

Hawk's beards

hawk's beards
crepis spp.

Ox's tongues

ox's tongues
picris spp.

Hawkbits

hawkbits
leontodon spp.

Goatsbeard

goatsbeard
tragopogon pratensis

Cat's ears

cat's ears
hypochaeris spp.

Goldilocks aster

Goldilocks aster
aster linosyris

Rare ragwort species

Fen Ragwort

fen ragwort
senecio paludosus

Welsh groundsel
senecio cambrensis

 

York groundsel
senecio eboracensis

 
Back to top