Species

Myriophyllum aquaticum

Etymology

Myriophyllum: many leaves

Common Name(s)

parrot's feather

Authority

Myriophyllum aquaticum (Vell. Conc.) Verdc.

Family

Haloragaceae

Brief Description

Sprawling emergent perennial herb with light grey-green foliage that is feathery in appearance (deeply divided). Submerged leaves are also finely divided and are often bright pink in colour.

Flora Category

Vascular - Exotic

NVS Species Code

MYRAQU

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

Dicotyledonous Herbs other than Composites

Distribution

Widely naturalised in the North Island (locally common in Auckland, Waikato, Wairarapa and Manawatu), rare but scattered throughout the South Island.

Habitat

Typically invades disturbed, polluted, high nutrient, well lit, still or slow-moving waterbodies. Wetlands, water margins, streams, rivers, slightly saline estuary edges and river mouths.

Features

Sprawling emergent perennial herb. Emergent leaves are a light grey-green, up to 3.5 cm long, and deeply divided (pinnate), giving them a feathery appearance. They are arranged in whorls of 4-6. The stem can be up to 2m long, but with only up to the top 10 cm emerging above water. Fibrous roots occur at the lower stem nodes. Submerged leaves are longer (up to 4 cm long, with filiform pinnae that are often bright pink in colour. Flowers in the axil of emergent whorls of leaves are white, tiny (up to 1.5mm across), with no petals. Only female flowers in New Zealand and other countires outside the native range.

Similar Taxa

Very similar to 5 native Myriophyllum spp all have stems less than 1 m long (except the endangered M. robustum). M. robustum is the most similar, M robustum is pointed at the leaf tip wheras M. aquaticum is rounded. May be confused with Ceratophyllum demersum but hornwort has forked rather than feathery foliage.

Flowering

September, October, November, December, January, February

Fruiting

No seed produced because only female plants in New Zealand.

Year Naturalised

1970

Origin

South America

Reason for Introduction

Ornamental aquarium and pond plant.

Life Cycle and Dispersal

Stem fragmentation and lateral stem growth. It does not produce viable seed in New Zealand, with only female flowers known to exist here. No seed produced because only female flowers. Fragments are dispersed by wave action or mechanical harvesting.

Tolerances

Can grow in fast-moving to still water; tolerant of occasional frosts and some salinity.

Attribution

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.

DiTomaso JM, EA Healy (2003).  Aquatic and riparian weeds of the west. University of California Agriculture and Natural Resources Publication 3421, 462pp.

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

Popay et al (2010).  An illustrated guide to common weeds of New Zealand, third edition.  NZ Plant Protection Society Inc, 416pp.

WSDE (2001).  An aquatic plant identification manual for Washington's freshwater plants.  Washington State Department of Ecology, 195pp.

This page last updated on 21 Aug 2013