Ceratophyllum demersum

Hornwort at Canberra Central, ACT

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Identification history

	Ceratophyllum demersum	2 May 2018	MichaelMulvaney
	Ceratophyllum demersum	28 Apr 2018	JaneR

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User's notes

Occasional strands found in shallow water on western side of Yarramundi Reach, Lake Burley Griffin, on 10th April 2018

4 comments

KenT wrote:

29 Apr 2018

Betty, the suggested identification looks right to me. I see dichotomously divided leaves so it is not a Myriophyllum and the teeth on the leaf segments (clear in 2nd image) excludes Cabomba caroliniana according to the Flora of Victoria. This species is not listed in the ACT plant census and PlantNET does not list it in the ST division, so I wonder if someone tipped the contents of an aquarium into the lake or if the seeds came in with fishing or boating activities.

JaneR wrote:

29 Apr 2018

Arrival as an an aquarium plant is unlikely (but not impossible) as its not a common aquarium plant (at least, not currently); and arrival by seeds is unlikely too (they sink to mud bottom). Most likely is contamination by people (boat propellers, waders) or even aquarium discards from vegetative fragments. But who knows when. Lake BG supported a variety of submerged macrophytes in 1970s necessitating weed control, these virtually disappeared in the 1980s. As far best I can determine, Ceratophyllum demersum was not named then.

KenT wrote:

29 Apr 2018

The name Ceratophyllum demersum is present in Linnaeus C (1753) Species Plantarum 2 p992 and this plant appears to have a cosmopolitan distribution. The first Australian record is Mueller, F.J.H. von in Hooker, J.D. (1859), The botany of the Antarctic voyage of H.M. Discovery ships Erebus and Terror. III. Flora Tasmaniae 2(10): 362 and it then appeared in Bentham, G. (1864), Flora Australiensis 2: p491. I haven’t come across any records for its presence in the ACT, my guess is that it is native to Australia but introduced to the ACT.

MichaelMulvaney wrote:

3 May 2018

A tricky one - is it a native weed? a re-introduction of a plant that used to occur here? or a rare relic? It has a cosmopolitan distribution - including over much of Australia. The nearest ALA records are Narrandera, Albury, Wallla (On upper Murray) and Narooma on the South Coast. I have labelled it as a cosmopolitan non-invasive species within our region, but could probably be convinced to change that rating.

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