Vascular – Exotic
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 lance-shaped leaves, with many tiny pink flowers held on a pyramid-shaped inflorescence, much taller than the rest of the plant.
Scattered in Hawkes Bay, Wellington and Canterbury.
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 7-23 (28) × 2-5 cm, with a tapered base with a long petiole up to or exceeding the leaf blade. Petiole is semi-circular in cross-section (D-shaped). Submerged or floating leaved plants sometimes occur, these have narrower than emergent leaves. 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.
Alisma plantago-aquatica has broader lance-shaped leaves and lilac rather than pink coloured flowers. Sagittaria platyphylla has larger flowers on a smaller inflorescence and triangular petioles.
Summer to autumn
Spreads by waterfowl and water dispersed seed.
Native to Europe, North Africa and West Asia.
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
Clapham, A.R.; Tutin, T.G.; Warburg, E.F. (1962). Flora of the British Isles. Cambridge University Press, Second Edition. 1269pp.
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.