Stem: Rigid and round

Leaves: Up to 2cm long and in opposite linear pairs. Leaf bases joined around the stem to form a collar. Leaves eshy when emergent and atter when permanently submerged

Flower: Very small with 4 whitish petals, flowers are often absent

Why Is New Zealand Pigmyweed A Problem?

Forms thick dense mats which can oat or be submerged. The thick mats cause shading of existing water plants and the depletion of oxygen in the water, which leads to a reduction of native ora and fauna.

Possible health hazard, as the thick mats can be mistaken for dry land.

The species can move onto a terrestrial habitat after it colonises an aquatic area. Can obstruct boats and reduce the opportunities where fishing can take place, which may impact upon local economies.