What makes a weed, a weed?

Weed Team Ranger, Summer, shares what makes a weed, a weed.

‘A weed is but an unloved flower’ - or, in our case, an unwelcome flower!

Just like the brush-tailed possum is a treasured native in Aussie and a pervasive pest in Aotearoa, what we consider a weed in Zealandia Te Māra a Tāne depends entirely on context. On my second day as a budding weed ranger, on some treacherous transect in the valley, I came across a small native sapling. A karo - recognisable by its leathery leaves with white fluff on the underside. I knew these trees can grow to over eight metres tall and that their flowers and fruit are favoured foods of birds like tauhou/silvereye. But then came the unimaginable when you’re working in an ecosanctuary dedicated to preserving native species. ‘You can pull that one out’ I was told. Did I hear that right or are my ears already filled with dirt?

Despite how wrong I felt in my soul removing this native (suffice to say I have hardened my heart since), my teammate Morag was bang on. Though karo are ecologically beneficial further north, their spread beyond their natural range into the Wellington region has landed them on Zealandia’s list of wanted weeds. This illustrates an important point about all the weeds we deal with - whether exotic, native or endemic, a weed is nothing more than a plant growing where it shouldn’t be.

I understand it like this: in the environment in which the plant first evolved, survival challenges like grazing herbivores, sunlight and moisture levels, access to pollinators and more naturally keep the plant’s growth in check. But put that plant in a new place without those limiting factors and you’ve got a wilful, wild weed on your hands.

Let’s take that karo story and go bigger. If karo is wreaking havoc a mere 100km away from its native range, imagine the tirade a plant from 10,000km away could embark on. Thanks to Wellington’s gorse-covered hills, it doesn’t require much imagination. These are huge problems. But what’s arguably more important for our ecosanctuary is the small-scale stuff - that 100cm difference from the inside of the fence to the outside, where a cherry tree can go from a garden darling to a trespassing troublemaker. I’d guess that within two months of being on the weed team, we’d probably pulled out over 100 of them.

We’ve created a safe haven for native wildlife within our fence, and our ongoing weed work ensures these unwanted plants are kept at bay so those that belong can thrive. But what if we treated the rest of Aotearoa like our sanctuary, and replaced those that don’t belong with those that do - our natives? We could do some pretty amazing things for our native ecosystems - in our home gardens, and our local outdoor spaces. Targeting weeds in our own backyards creates spaces for native plants, invertebrates and birds to thrive and prevents them from being spread far and wide – including into Zealandia.

If you’re in, a great place to start is to learn how to identify and recognise weeds. We’ve created this flow chart which will help you to identify Zealandia’s most wanted weeds: our ‘Hateful Eight’. While we tackle a range of other weedy species outside these, they’re our top priority. If you find one of these weeds while you’re walking in the sanctuary, you can upload its location to iNaturalist and one of our weed crew will come and deal to it. But in your own garden, it’s on you to remove it, so happy weeding!