Delta arrowhead

Delta arrowhead is an aquatic perennial herb that grows up to 1.2 metres tall. It is an aggressive invader and can quickly form dense infestations.

Description

• Submerged leaves are narrow and up to 50cm long.

• Emerged leaves are oval-shaped with a pointed-tip up to 48cm long with a central mid-vein.

• Flowers are 3 petalled, white, growing in groups of 3 on a leafless stem.

• Fruits are round clusters of one-seeded fruitlets.

• Rhizomes and corms (swollen, underground stems, similar to bulbs) are produced. The corms are 40mm long and are produced in response to stress.

• Seeds are dispersed by water, livestock, birds, and machinery. Can also spread via stems, root fragments, rhizomes, or corms.

• Habitats include drains, creeks, rivers, lagoons, and wetlands.

What you need to know

Delta arrowhead forms dense stands, displacing native aquatic vegetation. It can also trap sediment, infilling channels and blocking drainage ditches.

Management approach

Delta arrowhead is declared an unwanted organism by the Ministry for Primary Industries (MPI) because it is capable of causing harm to the natural environment, physical resources or human health in Aotearoa/New Zealand.

These species pose a high risk to our environment, economy, recreation, and cultural values.

Rules

Any species declared a pest, including unwanted organisms, cannot be sold or be in a place where plants are being sold. Pest plants cannot be propagated, bred, or multiplied, communicated, released, or cause to be released, or otherwise spread.

Control

Do not attempt to undertake control of delta arrowhead yourself. Report any sightings to us.