Species
Salvinia molesta
Common Name(s)
water fern
Authority
Salvinia molesta D.S.Mitch.
Family
Salviniaceae
Brief Description
Free floating fern with tightly overlapping hairy leaves, that forms dense growths on still and slow flowing waters.
Flora Category
Vascular - Exotic
Structural Class
Ferns
Distribution
Locally naturalised, subject to a national eradication programme since 1983, first record from Western Springs, Auckland in 1963.
Habitat
Still and slow flowing water bodies in warm areas. Prefers warm growing conditions and is susceptible to frost damage in a severe winter.
Features
Free-floating fern. Salvinia has a horizontal stem with paired aerial (above the water) leaves. Adult leaves brownish-green elliptic to broadly elliptic up to 2.5 x 2 cm, folded, whereas young leaves are flat. Aerial leaves have hairs shaped like miniature egg-beaters. Lower submerged leaves look more like roots and can be up to 30 cm long. Sporocarps in lond, straight chains, hairy c. 1 mm diameter produced under water.
Similar Taxa
The juvenile form resembles Azolla spp, but it is very distinctive when mature.
Flowering
N/A
Flower Colours
No Flowers
Fruiting
N/A
Year Naturalised
1964
Origin
South America, southeastern Brazil, and northern Argentina.
Reason for Introduction
Ornamental aquarium plant
Control Techniques
Notify Ministry for Primary Industries if found.
Life Cycle and Dispersal
Perennial. Spreads rapidly by fragmentation and producing plantlets from the old end of the horizontal axis, and can grow from a singe node; the death and decay of the older connecting part of the plant can lead to the separation of the viable younger branches. The plant is apparently a sterile hybrid. Fragments spread by water movement, deliberate release (with fish from aquaria)
Tolerances
Leaves are frost sensitive but can survive over winter in warmer parts. Generally requires high ligh and high temperature. Tolerates any quality of water, nutrient increases growth rate.
This page last updated on 21 Aug 2013