Species

Cabomba caroliniana

Common Name(s)

Cabomba, fanwort

Authority

Cabomba caroliniana A. Gray

Family

Cabombaceae

Brief Description

An obligate submerged, rooted aquatic plant that produces two different types of leaves. The most commonly seen submerged leaves, are oppostie and finely divided creating a fan shaped appearance. The floating leaves, are small, thin arrow shaped and occur during flowering. The flowers are attached to the bases of these small surface leaves. Flowers are small and white with a yellow interior, and sit just above the water surface.

Flora Category

Vascular - Exotic

Distribution

Only known from one site at Western Springs, Auckland, but a common plant in the aquarium trade.

Habitat

The NZ field site is a spring head, but C. caroliniana occurs in slow flowing and still water bodies in other countries. It is known from tropical to temperate regions, grows rooted in the substrate or free-floating, in stagnant and flowing water. It grows best in slightly acidic waters, but is not limited to them.

Features

Shoots are grass green to olive green or sometimes reddish brown. The leaves are of two types: submersed and floating. The submersed leaves are finely divided (palmately dissected) and arranged in pairs on the stem. They are fan-shaped, hence the name fanwort. The floating leaves, when present (usually when the plants flower), are linear and inconspicuous with the stem attached to the centre (peltate) and one end shallowly forked. They are ca 10 to 20 mm long and narrow. The flowers are small (10 to 20mm in diameter), mainly white with yellow at the base of the petals and float on or slightly emergent above the water surface. Each flower produces 2 to 4 leathery pods that contain 3 seeds (1 mm wide).

Similar Taxa

Hornwort (Ceratophyllum demersum) and Myriophyllum spp. Differs from hornwort and Myriophyllum spp. in that fanwort has leaves arranged in pairs (opposite), whereas the others have leaves arranged in whorls. Fanwort leaves do not have toothed margins, unlike those of C. demersum.

Flowering

Summer

Flower Colours

White,Yellow

Fruiting

Autumn

Year Naturalised

2009

Origin

Subtropic to temperate regiosn of eastern north and South America.

Reason for Introduction

Ornamental aquarium plant.

Control Techniques

Not managed in New Zealand. Notify regional council if found in wild.

Life Cycle and Dispersal

Sold widely in the aquarium trade, Spreads via stem fragments and rhizomes. Viable seed production not seen in New Zealand, but recorded in naturalised plants in Australia.

Attribution

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.

Kasselmann C (2003).  Aquarium plants. Krieger Publishing company, Florida, 518pp.

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

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

This page last updated on 21 Jun 2013