The New Zealand Plant Conservation Network

Species

Aponogeton distachyos

Etymology

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.

Common Name(s)

Cape pondweed

Authority

Aponogeton distachyos L.f.

Family

Aponogetonaceae

Brief Description

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.

Flora Category

Vascular - Exotic

NVS Species Code

APODIS

Structural Class

Monocotyledonous Herbs

Synonyms

Aponogeton distachyus

Distribution

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.

Habitat

Still and flowing water bodies.

Features

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.

Similar Taxa

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.

Flowering

Predominantly Decemeber, but spring to autumn.

Flower Colours

White

Fruiting

Autumn

Year Naturalised

1870

Origin

South Africa

Reason for Introduction

Probably planted as an ornamental because of its attractive, fragrant flowers.

Control Techniques

Can be controlled manually, mechanically or herbicidally depending on situation.

Life Cycle and Dispersal

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.

This page last updated on 31 Jul 2014