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.
Bottom rooted perennial aquatic plants that grows in water up to 1.2m deep with floating oval dark green leaves and attractive and fragrant flowers with white petals that extend above the water surface. Plants also have submerged leaves and large tuberous rootstock.
Widely naturalised, though apparently lost from some northern sites. Some locally abundant populations in coastal and lowland NI localities. Occurs in SI at Blenheim in Marlborough, in some lakes in Canterbury and Westland, near Dunedin and near Lake Te Anau.
Still and flowing water bodies.
Wetland plant indicator status rating
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Cape pondweed has a basal globose (nearly spherical) tuber, 3-4 cm in diameter. Floating leaves are basal, pale to dark green, up to 25 cm long, narrow-lanceolate in shape, and with many distinctive cross veins. Submerged leaves are linear in shape. The tuberous rootstock has a ring of long soft roots and fibrous remains from petioles. Flowers are on a two-forked spike with fleshy white lobes and are very fragrant. The terminal spikes (ca 6 cm long) protrude above the water and have a tubular spathe that sheaths the infloresence and falls off at an early stage . Flowers are sessile (no stem) in two rows and fragment at the base of the bract-like extensions of the spike axis. These bract-like extensions enlarge (ca 1cm) and become reddish at fruiting. Seeds are ca 9 mm long with a green spongy outer testa. Seedlings have terete/circular leaves and proressively acquire minature oblong leaves. When only a few centimetres high the seedling develops its characteristic basal tuber, and the testa remains attached to the seedling for a considerable period.
Swamp lily (Ottelia ovalifolia). Swamp lily has fibrous roots compared with the tuberous rootstock of Cape pondweed. Swamp lily floating leaves are less elongated, with pronounced dark green venation and flowers are three-petalled.
Predominantly Decemeber, but spring to autumn.
Seeds prolifically, seeds water dispersed. Ripe fruit can float for a short time before release of the negatively buoyant seeds and in flowing water the plant can be dispersed over considerable distance.
Reason for introduction
Probably planted as an ornamental because of its attractive, fragrant flowers.
Can be controlled manually, mechanically or herbicidally depending on situation.
aponogeton: From the Celtic apon ‘water’ and ‘geiton’ neighbour. An alternative etymology is that this word is from the Greek a- ‘without’ or ‘lacking’ and ge ‘earth, i.e. aquatic
distachyos: From the Greek dis ‘two’ and takeon ‘spike’, in reference to the V-shaped flower spike.
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.
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.