Water lettuce

Water lettuce is an aquatic weed that forms floating mats that look like lettuce.

Description

• Free floating perennial herb that produces stolons (horizontal stems) 60cm long and hairy.

• Leaves are light green, hairy, prominently ribbed, formed in lettuce-like rosettes, and have wavy margins.

• Roots are 45cm long and feathery.

• Flowers are minute and clustered.

• Fruits are small berries containing wrinkled disc-like seeds.

• Spreads vegetatively via stolons and seeds are wind dispersed

• Habitats include still and slow-flowing water bodies, lakes, dams, rivers, ponds, and streams.

What you need to know

Water lettuce forms dense mats, outcompeting native plants and reducing water quality. It can clog waterways, impeding drainage and recreational activities.

Management approach

Water lettuce 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 water lettuce yourself. Report any sightings to us.