Sagittaria

Sagittaria is an aquatic, perennial herb that can grow more than two metres tall.

Description

• Submerged leaves are strap like on young plants. Emerged leaves strongly resemble arrowheads on mature plants.

• Stems have 3 sides, which are soft and spongy.

• Flowerheads are leafless stems with 2-12 small white flowers and are purple at the base.

• Rhizomes are thick and vertical, producing buds.

• Seeds are wedge-shaped, winged, and brown.

• Seeds are dispersed by water, livestock, birds, and machinery. Buds from rhizomes can produce new plants.

• Habitats include still or slow-moving water body margins approximately one metre deep.

What you need to know

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

Management approach

Sagittaria 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 sagittaria yourself. Report any sightings to us.