(Ceratophyllum demersum)
Status of hornwort in Tasmania
What does hornwort look like?
Hornwort is a free-floating aquatic herb. The branched stems grow from 30 to 60 cm. The leaves are dark green, deeply divided into cylindrical segments which are toothed on one side, and occur in whorls of 5 to 12 leaves. The leaves are very crowded at the ends of stems so as to resemble a bushy animal tail. The flowers are greenish and very small. There are no roots; the roots are replaced by finely divided stem branches.
Hornwort overwinters as slowly growing plants, seeds or turions (called winter buds). Flowers are produced in summer but remain fully submerged.
Spread is mainly by vegetative means although seed can also be produced. Most spread is via stem fragments or turions which can be broken off by wave motion, foraging animals or boat propellers and floated downstream. Each stem fragment and turion can produce a new colony.
Hornwort, © Doreen L. Smith.
Impacts of hornwort
Hornwort is a native plant in ponds, dams and streams on mainland Australia, and only becomes a weed when the freshwater system is altered, particularly where nutrient levels are enriched.
Where does hornwort occur?
What you need to do
See also
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