water celery, fool’s watercress
Apium nodiflorum (L.) Lagasca
Vascular – Exotic
Herbs - Dicotyledons other than Composites
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.
Sprawling emergent perennial aquatic plant that can grow over a metre in height, with bright green leaves arranged in pairs up each stem, and white flowers close to leaf bases.
Scattered distribution from Northland to Wellington, abundant in many areas. Has also established in the north and west of the South Island.
Shallow water ponds, drains, and the margins of slow moving streams.
Wetland plant indicator status rating
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Stout perennial herb with prostrate and ascending stems. The stems are hollow, finely furrowed, may be up to 2m long and root at the lower nodes. The leaves are glossy, bright green to 70 cm long with 2 to 8 pairs of toothed stalkless oval to lance-shaped leaflets. The individual flowers are small (2 to 2 mm) with five white petals, and occur in short stalked clusters/umbels (2 to 4 cm) in diameter. The fruit are dark brown, small (2mm long) and ovoid/egg shaped and ribbed.
Wild celery (Apium graveolens), New Zealand celery (Apium prostratum) and Watercress (Nasturtium spp.). Wild celery is similar but does not root at the nodes, and NZ celery has thicker three lobed and shortly pinnate leaves.
November to February
Late summer to autumn
Seed germinate on damp substrates. Regrows from detached shoots, which readily form roots, and from seed.
It can be mistaken for watercress and be collected and distributed as such.
Native to Britain, central Europe, Asia and North Africa.
Reason for introduction
Possibly seed contaminant or contaminant of ornamental pond plants.
Can be controlled manually, mechanically or herbicidally depending on situation (Newman, 2004).
Seed germinate on damp substrates.
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).
References and further reading
Johnson PN, Brooke PA (1989). Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319pp.
Newman J (2004), Information sheet 28: Fools watercesss. Centre for Ecology and Hydrology , UK.
Popay et al (2010). An illustrated guide to common weeds of New Zealand, third edition. NZ Plant Protection Society Inc, 416pp.
Johnson, A. T., Smith, H. A. (1972). Plant Names Simplified: Their pronunciation, derivation and meaning. Landsman Bookshop Ltd: Buckenhill, UK.