Cabomba caroliniana
Common names
Cabomba, fanwort
Biostatus
Exotic
Conservation status
Not applicable
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Simplified 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.
Flower colours
White, Yellow
Detailed description
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.
Distribution
Originally known from one since destroyed site at Western Springs, Auckland, but found to be at Paremuka Lakes, Henderson in 2016. A common plant in the aquarium trade.
Habitat
The NZ sites are a spring head and a group of man-made lakes, 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.
Detailed taxonomy
Genus
Family
Ecology
Flowering
Summer
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.
Referencing and citations
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.
Attribution
Prepared by Paul Champion and Deborah Hofstra (NIWA)