Beware of nasty pond dweller

Delta Arrowhead originally hailed from the south-eastern United States and very probably migrated to the shores of Aotearoa to begin a new life as a pond ornamental.

However, when it is allowed to wander unsupervised, it can wreak havoc in our local waterways, blocking watercourses, drains and closing in larger bodies of water without a conscience to speak of.

It has not arrived in the Wellington Region yet and we are keen to keep it that way.

This plant is a born survivor with a number of ways to reproduce built into its DNA and it is has many means of moving about, via a very comprehensive rhizomatous root system, also by producing hundreds of seeds.

Fortunately, its one saving grace is that it hasn’t been known to flower in New Zealand, in turn cutting out seed production which it would normally have in its propagation arsenal. It has long, thin submerged leaves and also distinctive lance shaped emergent leaves on stems.

As with all aquatic weeds, control is difficult. To prevent spread of this species, and indeed all aquatic plants, great care should be taken to remove all plant material from boating and recreational equipment before heading to another water body.

Delta Arrowhead can be controlled by mechanical means, hand digging can be used for small infestations, however, care must be taken to remove all rhizomes and plant pieces from the water as any escapee fragment has the propensity to find itself a new home relatively easily and quickly.

Our waterways are incredibly delicate, and any new threat should be addressed without delay to ensure the continued health and wellbeing of our country and our people.

If you think you have seen this plant, or need help with identification on a possible sighting, phone Greater Wellington Regional Council on 0800 496 734, email pest.plants@gw.govt.nz , or alternatively check out the pest plant pages at www.gw.govt.nz.