Species

Potamogeton crispus

Etymology

Potamogeton: river dweller

Common Name(s)

curly pondweed

Authority

Potamogeton crispus L.

Family

Potamogetonaceae

Brief Description

Submerged aquatic plant that has green to red/brown leaves arranged alternately on stems. the leaves are ca 10mm in width and up to 80 mm long with distinct wavy edges (hence the name 'crispus'). Centre veins of the leaves are normally reddish.

Flora Category

Vascular - Exotic

Plant Code

POTCRI

Structural Class

Monocotyledonous Herbs

Distribution

Widely naturalised throughout New Zealand, rare in West Coast Region

Habitat

Moderately fast flowing to still water bodies.

Features

Entirely submerged, bottom-rooting, normally perennial. Slender rhizomes and roots. P. crispus has long branched stems, that feels slightly flattened (as opposed to round or cylindrical), with submerged leaves that are arranged alternately on the stem. The leaves are green to reddish brown, slightly translucent, about 10mm in width, and up to 80mm long. Leaf margins are markedly wavy and crimped, with fine teeth near the tip. Centre veins of the leaves are normally reddish. The inflorescence spike has few flowers. Flowers small, green, on spikes up to 1 cm long, 4 flat dark seeds. The fruit (achenes) are large (4mm) and thick, with a curved beak and a toothed (rounded toothed) dorsal keel. Turions or winter buds of hard scales formed by shortened, thickened leaves with broad and strongly toothed bases.

Similar Taxa

Potamogeton ochreatus and P. cheesemanii. P. ochreatus has a straight edged leaf and a blunt leaf tip, whereas curled pondweed has a rounded leaf tip with crimped edges. It can be distinguished from P. cheesemanii by the submerged leaves, which are narrower and much more crimped in curled pondweed.

Flowering

November, December, January

Flower Colours

Cream,Green

Fruiting

Autumn

Year Naturalised

1940

Origin

Native to Europe, Asia, Africa and Australia.

Reason for Introduction

Ornamental pond and aquarium plant

Control Techniques

Not usually controlled in New Zealand, but may be controlled manually, or mechanically.

Life Cycle and Dispersal

Spread by seeds, stem fragments, rhizomes, or turions. Birds disperse seed, fragments, rhizomes and turions dispersed by contaminated machinery and water movement.

Tolerances

Tolerates brackish, flowing or still water, and grows to 10 m depth.

Attribution

Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).

References and further reading

Champion et al (2012). Freshwater Pests of New Zealand.  NIWA publication. http://www.niwa.co.nz/freshwater-and-estuaries/management-tools/identification-guides-and-fact-sheets/freshwater-pest-species.

Johnson PN, Brooke PA (1989).  Wetland plants in New Zealand.   DSIR Field Guide, DSIR Publishing, Wellington. 319pp.

Coffey BT, Clayton JS (1988).  New Zealand water plants:  a guide to plants found in New Zealand freshwaters.  Ruakura Agricultural Cente. 65pp.

Aston, H (1977).  Aquatic plants of Australia. Melbourne University Press, 367pp.

This page last updated on 21 Aug 2013