Species

Alisma plantago-aquatica

Common Name(s)

water plantain

Authority

Alisma plantago-aquatica L.

Family

Alismataceae

Brief Description

A marginal aquatic plant, with wide lance-shaped leaves, with many tiny pale lilac flowers held on a pyramid-shaped inflorescence, much taller than the rest of the plant.

Flora Category

Vascular - Exotic

NVS Species Code

ALIPLA

The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.

Structural Class

Monocotyledonous Herbs

Distribution

Scattered and locally common from Northland to northern Southland, but absent from large parts of southern aMargins of still and slow flowing water bodies and wetlands.nd eastern North Island and eastern South Island.

Habitat

Margins of still and slow flowing water bodies and wetlands.

Features

Leafy emergent perennial herb up to c. 1 m high, although non-flowering plants are much shorter. Aerial parts die off over winter to the rootstock. Leaves all basal, broad ovate 8-20 × 3-10 cm, with a rounded base with a long petiole up to or exceeding the leaf blade. Petiole is semi-circular in cross-section (D-shaped). Inflorescence a large, much-branched panicle; branches whorled. Flowers usually pale lilac, c. 1 cm across. C. 20 rounded and flattened seeds (achenes) c. 2.5 mm long, in a dense circular head (Croasdale et al., 1994).

Similar Taxa

Alisma lanceolatum has narrower leaves and pink rather than lilac coloured flowers. Sagittaria platyphylla has larger flowers on a smaller inflorescence and triangular petioles

Flowering

Summer

Flower Colours

Lilac,Red / Pink,White

Fruiting

Summer to autumn

Year Naturalised

1929

Origin

Native to Northern Temperate regions and Australia.

Reason for Introduction

Possibly ornamental pond plant, or a seed or soil contaminant.

Control Techniques

Rarely problematic and normally controlled in New Zealand.

Life Cycle and Dispersal

Spreads by waterfowl and water dispersed seed.

Attribution

Prepared by Paul Champion and Deborah Hofstra (NIWA).

References and further reading

Aston, H.I. (1977).  Aquatic plants of Australia.  A guide to the identification of the aquatic ferns and flowering plants of Australia, both native and naturalised.  Melbourne University Press.  368pp.

Croasdale, H., Flint E. A. and Racine, M. M. (1994).  Flora of New Zealand Volume 3: Freshwater algae, chlorophyta, desmids with ecological comments on their habitats, Staurodesmus Staurastrum and the Filamentous desmids. Manaaki Whenua Press: Lincoln, New Zealand.

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

Preston, C.D.; Croft, J.M.  (1997). Aquatic plants in Britain and Ireland.  Harley Books, 365pp. 

This page last updated on 10 Jan 2014