Wellington recently competed in the iNaturalist City Nature Challenge. During the four days of the Challenge people recorded as many observations and species as possible. Science researcher Lara Shepherd was shocked that the introduced weed old man’s beard was the second-equal most observed species in Wellington.
Given that the City Nature Challenge by definition occurs in cities, I was anticipating garden plants and weeds to feature strongly. However, I did not expect one of New Zealand’s worst weeds, old man’s beard, to tie with māhoe as the second most observed species in Wellington!
What is old man’s beard?
Old man’s beard (Clematis vitalba) was introduced to New Zealand as a garden plant sometime before 1922.
It is a woody climbing vine that is related to the nine native species of Clematis. Old man’s beard can be distinguished from native Clematis species by its deciduousness, its flowering during summer and autumn, its furrowed bark and leaves with five leaflets (rather than three).
Why is old man’s beard a problem?
Old man’s beard has a number of features that make it a particularly bad weed. It has a high shade tolerance so can invade established native forest. It is a very vigorous vine that can grow up to 4m per year.
Old man’s beard forms dense thickets that can smother and kill native plants and prevent native species regenerating.
It produces a very high number of seeds that can spread by wind, water and birds. These seeds can survive for 8–10 years in the soil and pieces of stem can re-sprout where they come in contact with the ground.
Old man’s beard was first recognised as a serious environmental weed in the 1980s and millions of dollars has been spent on its control across the country.
Is old man’s beard spreading in Wellington?
I have noticed over the last few years that old man’s beard is increasing in my neighbourhood. And comments on online native plant discussion forums suggest that it is becoming more common all across Wellington.
This increase likely relates to the recent decrease in control efforts. Wellington City Council (WCC) used to control old man’s beard in its open space and road reserve land, with the aim of preventing plants seeding.
However, now WCC only undertakes weed control in reserves of high conservation value and allocates enough funding to control weeds in about 8% of Wellington’s reserves. This means that old man’s beard is not controlled on many of the roadside reserves around the city, because these sites are considered to not have high ecological value.
In the wider Wellington area the Greater Wellington Regional Council previously controlled pest plants like old man’s beard on private property. However, they no longer do this and now encourage private landowners to control such weeds themselves. The Hutt City Council still controls some weeds, such as old man’s beard, on private property but they have a limited budget.
Old man’s beard must go – but how?
Around the city we are embracing pest animal trapping. However, our pest plants are flourishing. But to quote David Bellamy’s iconic TV advert from the 1980s, “old man’s beard must go!”
On private land it is currently up to Wellingtonians to control old man’s beard. If you have old man’s beard on your property, you can remove it, with tips on control available on the Greater Wellington website. Encourage or help your neighbours to also remove it from their properties.
You can report old man’s beard in WCC reserves using their form (including photos to show the size and context of the plant(s) with location details), although control will only be undertaken in priority reserves.
If you think that the WCC should be controlling old man’s beard beyond just high ecological value reserves then let them know. I think WCC should be controlling old man’s beard on all steep hillsides in Wellington, where access is unsafe for the public.
For reserve land of supposed ‘low ecological value’, such as road reserves and much of the town belt, it is presently up to individuals and community groups to control old man’s beard. There are a number of regional restoration groups who undertake weeding like this Facebook group Old Man’s Beard Must Go – Aro Valley. If your neighborhood doesn’t have such a group you could set up your own.
Without further control old man’s beard may quickly become the most common species in Wellington!
Read about some of the highlights from Wellington’s City Nature Challenge 2021