Despite being intentionally cultivated for over 100 years, Boston ivy has started to naturalise across three cities in New Zealand at the same time. Ewen Cameron, Curator Botany, and Botany volunteer Shelley Heiss-Dunlop recently penned an article to shed some light on this discovery, and what it might mean for our environment. 

Boston ivy (Parthenocissus tricuspidata) is a long-lived woody vine that can fasten on to walls and buildings by the sticky disc-like tips of the branched tendrils. As with many common plant names, “Boston ivy” is misleading – it is neither from Boston, nor an ivy. It is actually native to eastern Asia (Korea, Japan, northern and eastern China) and is in the grape family, Vitaceae. It is so commonly cultivated in the USA, especially on their university buildings, that it is the “ivy” of their Ivy League. Around Auckland it is commonly cultivated in the older suburbs, usually covering walls or fences, sometimes covering buildings. Boston ivy’s leaves are usually 3-pointed or trifoliate, which separates it from its two relatives which are also in New Zealand: Virginia creeper (P. quinquefolia) and false Virginia creeper (P. inserta, syn. P. vitacea) that both have 5-leaflets.

Boston ivy fully in leaf with fresh, apple-green leaves in spring, covering the Northern Club building, 19 Princes St, central Auckland. Photo: EKC, 16 Nov 2021.
A mystery takes root

A mystery takes root

In April 2019 a mystery seedling with trifoliate leaves was observed in a pot plant under an outside tree at the home of Ewen Cameron (Curator Botany) in Auckland. In autumn the leaves turned red and dropped off. Fortunately, it sprouted new trifoliate leaves in the spring. After some time, the seedling was identified as Boston Ivy, but the closest known adult vine was some 100 metres away.

Ewen published an article (Cameron 2021) about the discovery, claiming that it was potentially the first recorded wild Boston ivy seedling in New Zealand. In response to this article, three people from across the country wrote in to share their findings – wild Boston Ivy seedlings in Christchurch, Nelson, and at another two homes in Auckland.

52 seedlings at cotyledon stage, some with the start of the first true leaf to 4 mm long, from 52 seeds sown on 22 Jul 2022. Photo: EKC 17 Oct 2022. Scale: most are 15-16 mm wide × 17-18 mm long.

Further investigating revealed even more instances of self-established seedlings sprouting up across Auckland, and the problem is likely more widespread than what’s been documented so far.

To find out how commonly Boston ivy is establishing itself by seed, Ewen, and Museum Botany volunteer Shelley Heiss-Dunlop recently jointly published an article (Cameron & Heiss-Dunlop 2022) outlining these seven different localities and encouraged members of the Auckland Botanical Society to examine their surrounds for more juvenile plants.

Already three new localities have been reported. These naturalisations of seedlings are pressed, dried, mounted on card and form a permanent record as specimens in the Museum’s extensive herbarium collection. You can explore some of these records through Collections Online.

A potted-up Boston ivy seedling; a second seedling uprooted behind (now AK 385292), St Albans, Christchurch. Photo: Anthony Wright, 15 Oct 2022. Scale: pot 140 mm diam.
A case of naturalisation?

A case of naturalisation?

What has changed so that these long-established Boston ivy vines now appear to be producing wild seedlings for the first time in New Zealand? Is this just a short-term event, or is it part of a long-term climate change – are we about to see wild Boston ivy seedlings becoming abundant near established plantings, and spreading?

This phenomenon is called naturalisation. Naturalisation is when a cultivated, non-native/exotic plant “misbehaves” and starts to spread by itself with no human involvement. This usually occurs by seed: seeds with a wing (e.g. pine trees) or a parachute (moth plant), or “dust” seeds (eucalyptus) all get blown; some seeds can float on water (some wattles); others can attach to birds or mammals (bastard grass), others with fleshy fruit get ingested (rhamnus) by birds or mammals; and a few just keeping spreading vegetatively rather than spreading by seed (spreading bamboo species).

Planted Boston ivy vines 450m along concrete retaining wall, southern motorway, seen from Dilworth footbridge looking south towards the Market Road offramp. Photo: SHD, 24 Oct 2022.

Boston ivy is insect pollinated (by flies, wasps, bees) and each fleshy fruit contains 2-3 seeds. The blue-black ripe fruit (8 x 5mm) is eaten by frugivorous birds, e.g., starlings or tui, which widely disperse the seed.

This could be the start of a large naturalisation, or it might be the result of a short-term unusual weather event. Time will tell – however, it certainly warrants monitoring at this stage. There are now more wild exotic vascular plant species in New Zealand than native species. Large vine species that naturalise, like Boston ivy, pose a distinct threat to native plants – they can smother them, and also by climbing up on trees they may pull them down with the extra weight.

On the fence, Cornwall Park. Leaves turning red and dropping off at the end of summer, exposing the ripening fruit for birds to digest. Photo: SHD 1 Mar 2022.
What happens next

What happens next

The next step will be to collect feedback and pass it onto Regional Councils who may want to review their rules about how Boston Ivy is managed, grown, and sold in New Zealand.

If you think you’ve found a rogue Boston ivy seedling, we want to know about it. Either send an image/specimen to the Museum or share your finding on iNaturalist, an active international network dedicated to sharing observations of biodiversity.

What to look out for:

  • Juvenile trifoliate leaves (3 separate leaflets)
  • Green leaves that turn red in April / June 
  • Circular pads at the end of tendrils for sticking to surfaces

Seedling specimen AK 385291 held on permanent record in the Auckland Museum herbarium.


Cameron, E.K. 2021: Boston ivy (Parthenocissus tricuspidata) – the first wild seedling in New Zealand? New Zealand Botanical Society Newsletter 146: 10–​12.

Cameron, E.K.; Heiss-Dunlop, S. 2022: Boston ivy (Parthenocissus tricuspidata) – reacting to climate change in New Zealand? Auckland Botanical Society Journal 77: 124–130.

Adult simple, 3-pointed leaves mostly produced from older wood. Northern Club building, 19 Princes St, central Auckland. Photo: EKC, 16 Nov 2021.