Illustrated Guide to
of New Zealand
Weeds of New Zealand
by Ian Popay, Paul Champion & Trevor James
ISBN 0 473 09760 5
by kind permission of the
Zealand Plant Protection Society
Publication or other use of images or descriptive
text on these pages is unauthorised unless written permission is
obtained from the authors and publisher.
of the publication Common Weeds of New Zealand must always
Available from Touchwood
free-floating or lightly anchored, rootless, delicate aquatic perennial.
Has forked, finely divided leaves. Forms very dense under-water
masses of vegetation in freshwater up to 10 m deep.
- Flowers Green
(female), whitish (male), no petals, minute. Solitary in leaf
axils, stalkless, with ten to twenty stamens, adapted for underwater
- Fruit Black
oval nuts 5 mm long, with one terminal and two basal spines.
- Leaves Dark
green, up to 4 cm long, in whorls of seven to twelve densely crowded
at the stem apex and increasingly spaced down stems. Leaves equally
forked once or twice into rather stiff, tapering segments.
- Stems Floating,
submerged, up to 1.5 m long, branched, stiff and rather brittle.
Readily broken by waves, current or boats to float away and establish
in shallow water.
No roots, lightly anchored in sediment by buried leaves and stems.
Still or slow-flowing
freshwater of lakes, lagoons, ponds, rivers and drains.
Locally abundant in
the Waikato River system including hydro lakes. Common in Auckland,
Waikato, Rotorua Lakes, Taupo, Hawkes Bay and Wellington in NI.
Found throughout the world.
May be confused with
parrot's feather (Myriophyllum aquaticum) which has pinnate,
rather than forked leaves. Listed on the National
Pest Plant Accord (see Introduction for details).
of botanical name
= horned leaved, the leaves resembling antlers; demersum (Lat.)