An invasion of pink ragwort.

If you have recently travelled along SH1 between Wellington and Paekakariki you may have noticed that some of the roadside cuttings and banks are tinged with pink. The culprit is the daisy pink ragwort (Senecio glastifolius).

Pink ragwort flowers. THe flowers can range in colour from purple to nearly white. Photo: Lara Shepherd.

Pink ragwort flowers. The flowers can range in colour from purple to nearly white. Photo: Lara Shepherd.

Pink ragwort is native to a small area of coastline in South Africa and was first recorded in New Zealand in Gisborne in 1963 and in the Wellington region soon after. How it reached our shores is unclear as there are no records of plant nurseries growing or selling it. Pink ragwort subsequently spread to other areas of  New Zealand, with some movement probably occurring through its deliberate planting as an ornamental garden plant. It is primarily a weed of open areas including disturbed ground, agricultural land and coastal areas.

Pink ragwort plant, coast near Titahi Bay. Photo: Lara Shepherd

Pink ragwort growing on the coast near Titahi Bay. Photo: Lara Shepherd

A recent thesis by Victoria University of Wellington student Josef Beautrais examined the spread of this weed. Using species distribution modelling, Josef found that pink ragwort is occupying a different niche in New Zealand to what it occupies in its native South Africa. Of more concern, he found that there are large areas, including the northern third of the North Island, that offer suitable habitat for pink ragwort but that have not yet been invaded by this species. 

Pink ragwort is common on the coast south of Titahi Bay. Photo: Lara Shepherd.

Pink ragwort is common on the coast south of Titahi Bay. Photo: Lara Shepherd.

Should we be worried about pink ragwort and its growing distribution? In many disturbed sites, which are already full of weeds, it isn’t too much of a concern. However, it is a serious threat to coastal sites where it can crowd out low-growing endangered native species such as Pimelea actea and Sebaea ovata. It is banned from being sold and propagated in Taranaki and Northland and is being controlled at some sites near Whanganui.

14 Responses

  1. Stephen Hartley

    Josef’s modeling suggests that cold winters (particularly frosts) are the main limiting climatic factor in New Zealand, one reason it appears to thrive in coastal areas.

    Reply
    • Lara Shepherd

      Thanks Stephen. Its good to hear something is limiting it!

  2. Mike Lusk

    It is common in Hawkes Bay too, and colonises limestone cliffs and dunes, but grows best in good soils. Northland already has a near relative S. elegans (aka purple ragwort) growing in, at least, coastal situations including dunes.

    Reply
    • Lara Shepherd

      Thanks Mike, I didn’t realise it was common there too. Is purple ragwort less invasive than pink ragwort?

  3. Leon Perrie

    Alongside Lara’s NatureWatch suggestion, specimens that add to Te Papa’s current holdings would be welcome – see the map here: http://collections.tepapa.govt.nz/Taxon/17963

    Reply
  4. Mick Parsons

    I have noticed it as far north as Alton. I was wondering if inland soils may be a bit heavy or damp for it. I am asking others to see if they have noticed it further around the coast.

    Reply
    • Lara Shepherd

      Recording the spread of pink ragwort would make a great citizen science project. You don’t have to be a botanist to identify it, at least when its flowering, and I’m sure regional councils would like help tracking its spread. Existing records on Nature Watch don’t represent its current distribution (http://naturewatch.org.nz/taxa/336367-Senecio-glastifolius) – so get recording everyone!

  5. Phillip

    Has it got to Auckland yet?

    Reply
  6. Sean Mallon

    Pink ragwort is common throughout Tawa…it joins my list of least popular plants including agapanthus.

    Reply
  7. sylvia

    I think it’s pretty and love how Wellington pinks up as summer comes. However if it’s really a threat….sigh…I guess we have to discourage it.

    Reply
  8. Julia White

    I would like it all killed now. It looks awful

    Reply
    • Mick Parsons

      Fat chance of any control attempts working now! It now occupies most recently logged (disturbed) sites throughout South Taranaki. There has been a flurry of inquiries in the region as to what it is this year even though it has been around for over 5 years. It is interesting to note how long a community notices what might be a ‘pretty thing’ in a waste area for some years may be something else and become alarmed about it. Does not seem to be an agricultural weed as it does not compete with pasture plants and livestock seem not to be deterred by it. Coastal areas with constant disturbance must be a worry when so many of our rare native plants depend on this same disturbance.

    • Lara Shepherd

      Have you noticed it spreading north in Taranaki, Mick? I think the big concern is that if it can get around the mountain then the prevailing wind will blow its seeds all over the Waikato.

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