Vascular – Exotic
Herbs - Monocots
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.
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.
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.
Margins of still and slow flowing water bodies and wetlands.
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).
Alisma lanceolatum has narrower leaves and pink rather than lilac coloured flowers. Sagittaria platyphylla has larger flowers on a smaller inflorescence and triangular petioles
Lilac, Red/Pink, White
Summer to autumn
Spreads by waterfowl and water dispersed seed.
Native to Northern Temperate regions and Australia.
Reason for introduction
Possibly ornamental pond plant, or a seed or soil contaminant.
Rarely problematic and normally controlled in New Zealand.
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.