Senecio inaequidens

Taxonomy 

Common name: Narrow-leaved Ragwort.

Synonyms: S. lautus auct.; S. burchellii auct. (Sell & Murrell 2006).

Chromosome No.: 2n = 40 (Stace 2010).

Senecio inaequidens

Photograph: Q. Groom

Identification 

Identification This species resembles Oxford Ragwort, S. squalidus, in many aspects of its habit and habitat. It is easily distinguished by its narrower leaves and sometimes rather woody, fibrous stems - as S. inaequidens is a perennial, unlike the predominantly annual ragworts likely to be found in similar habitats.

Distribution 

The species comes from Southern Africa and is now found across Europe; North, Central and South America; Australia and Hawaii. It was first found in Europe in Fife, v.c. 85, in 1834 (G.H. Ballantyne, pers. comm.). In Britain, as in the rest of Europe, early records were usually associated with waste from the wool processing industry. However, it was not until the 1970’s that it began to naturalize and spread, first in Germany, but now right across Northern Europe. Visitors to the channel ports of Calais, Boulogne, Dunkerque and Oostende will have no difficultly finding it in abundance. Stace (1997) described it as naturalised in one site in Kent and predicted (accurately, as it turned out) that it would soon spread.

BSBI Hectad Map 

Click on the map to view full-size on the BSBI Maps Scheme website.

Ecology 

When the New Atlas (Preston, Pearman & Dines 2002) was published at the turn of the millennium it was still described as largely a casual with only two populations where it had more or less naturalized. However, by 2008 the Maps Scheme shows that it has naturalized in at least 10 vice counties, including some large populations, particularly in and near London.

In Britain, as in Europe, it grows predominantly in ruderal sites, notably along side major roads, railway tracks, car parks, pavement cracks and demolition sites. It can also be found in more natural habitats, particularly close to the sea. Its current distribution in the UK shows a bias towards coastal areas; though these are often the sites of major sea ports, where the seeds are easily accidentally imported from continental Europe.

Status 
  • Origin: alien.
  • Rarity: in recent years it has become quite widespread in England and Wales, and it has appeared in Scotland and Ireland.
  • Threat: not threatened.
  • Conservation: as a largely synanthropic species it poses no obvious threat to native plants or vegetation.
Further Work 

The spread of Narrow-leaved Ragwort presents an opportunity for further study into the behaviour of invasive aliens. There is no evidence yet that it is a problem weed in any habitat, and no cause to eradicate it. There are no studies yet published in Britain on its ecology, dispersal or associations.

Sell (2006) describes it as a frequent wool alien; but is this simply repeating previous accounts, or is wool shoddy still a significant vector in its dispersal?

Citation 
Groom, Q.J. (Date accessed). Species account: Senecio inaequidens. Botanical Society of the British Isles, www.bsbi.org.uk.

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