PEST PROFILE: Russell lupin, Lupinus polyphyllus
Every year, Aotearoa’s river systems and lakes attract thousands of visitors: anglers, trampers, kaitiaki, researchers, and tourists. Many come with cameras, hoping to capture the magic these special places have on offer. Russell Lupins, particularly around Tekapo and throughout Canterbury, have become a popular photography subject, as well as inspiring vigorous debate, with some not understanding that this exotic weed threatens the endangered riparian and lake-shore species that make these ecosystems so unique . . .
Native range:
Streams and lakes of Western North America. This plant is generally hardy, able to endure frost, and recover from heavy grazing and damage, even submersion in water. However, it’s intolerant of both drought and shade – hence its love of shore-side locations.
Arrival in Aotearoa:
The most striking feature of the Russell Lupin is their tall spikes of flowers, creating floral seas of pinks-and-purples wherever they proliferate. From the 1930s, lupins were popular addition to gardens, from where they spread into the wild. The seeds may have also been deliberately spread in misguided attempts to beautify areas of deforestation or starker endemic vistas. Lupins around Tekapo have particularly thrived in part with their picturesque views as a tourist attraction.
Riparian takeover:
Endemic birds like kakī and wrybills already have it tough, contending with a slew of invasive predators like stoats and the ravenous hedgehog. Every chick counts towards the future survival of these taonga manu (treasured birds). Lupin invasion adds to their struggle by drastically altering natural nesting sites, both by smothering riverbeds with vegetation (providing cover for ambush predators), and even changing the flow of rivers through sand and gravel build-up.
Species at risk: Habitats at risk:
Kakī /Black stilt Riverbeds
Ngutu parore/Wrybill Lake-shores
Tūturiwhatu/Banded dotterel
Not So Tasty |
Many members of the genus Lupinus (which Lupinus polyphyllus belongs) contain toxic alkaloids: when crushed, the seeds of the Russell lupin are poisonous to eat. While some agriculturalists champion lupins as a nutritious sheep feed, in Australia the ingestion of Lupinus plants infected with a fungal pathogen (Diaporthe toxica) has caused liver disease in sheep. |
What keeps the Russell lupin in check in its natural range?
In America, several native beetle, butterfly and moth species feed on the alkaloid-laden leaves of lupins. An array of competing plants also helps keep everything in balance.
Action stations!
The Russell Lupin can be weeded out manually, and herbicides can be employed to prevent regrowth. In areas where restoration is appropriate, regenerating natives can prevent re-invasion by blocking out the sun.
Importantly, public awareness of the damage the Russell Lupin can inflict is vital in helping nature-loving kaitiaki (guardians) make good decisions when lupins are concerned.
Download Find-a-Pest, and report Russell Lupin infestations to help keep Aotearoa’s river systems thriving.