# Aquatic plants are plants with C4 or C3 photosynthesis?



## macek.g (5 Nov 2021)

Hi All
Specifically, I mean *aquatic plants*, if they are C3 as I think then everything is clear to me.
  Egeria densa is a C4 plant?


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## sparkyweasel (5 Nov 2021)

Apart from_ Egeria densa_ the only other true aquatic C4 plant currently known is _Hydrilla verticillata_.
Ref; C4
However some aquarium plants are not considered aquatic by botanists, such as some _Eleocharis _and _Cyperus _species which are C4.
At least one species, _Eleocharis vivipara _uses C3 in its submerged leaves and C4 in its emergent leaves.
hth


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## Karmicnull (5 Nov 2021)

sparkyweasel said:


> Ref; C4


Fascinating article - thanks for sharing.


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## ceg4048 (6 Nov 2021)

There is another category similar to C4, called CAM (Crassulacean Acid Metabolism).
CAM plants uptake CO2 at night and stores it as malic acid. Then extracts and uses the CO2 during the day.
CAM plants are typically in arid terrestrial environments, but there are an aquatic versions in the genus Isoetes, commonly known as "quilweeds."

Cheers,


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## Tyko_N (6 Nov 2021)

Aren't _Vallisneria sp _CAM plants as well? I remember reading it somewhere earlier and found an old article substantiating it (CAM Photosynthesis in Submerged Aquatic Plants), as well as saying that _Sagittaria _and _Littorella_ used CAM too, but maybe there are more recent results?


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## John q (6 Nov 2021)

@Tyko_N  I think that link requires a log in, here's the pdf.
Also a recent article that ties in with what Clive mentioned Underwater CAM photosynthesis elucidated by Isoetes genome - Nature Communications


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## macek.g (6 Nov 2021)

The conclusion is that ,most of the popular plants we have (rotala, ludwigia, hygrophila etc etc) are plants with c3 photosynthesis with some exceptions with c4 photosynthesis.

Tahnk you


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