I am wondering if aquatic plants have stomata or not. I know that non-aquatic plants have stomata to release water(transpiration) and oxygen, and to take in carbon dioxide. Do aquatic plants also have stomata, and if so do they take in water through their stomata? If water is taken in through their stomata, wouldn't other substances such as dissolved salts get in the plants vascular system too? Does the aquatic plant use this salt or remove it, and how would they remove it?

Note: I am talking about fully submerged aquatic plants such as kelp.



First of all, stomata is of course important for gas exchange and also water conservation. Well, clearly, water conservation isn't needed! Also, gases can diffuse relatively easy in water so gas exchange using stomata isn't needed.

Technical notes

Second of all, technically organisms like kelp are thalloid plants. They are in separate kingdoms. Kelp is a brown algae, placed in kingdom algae in laminariales order of class phaeophyta. They does not contain any kind of vascular or conductive tissue as their plant body is thalloid.

  • $\begingroup$ @zack1544 you're welcome. If you have related questions, please ask me in the comments. $\endgroup$ – TanMath Nov 11 '15 at 3:15
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    $\begingroup$ They're not in separate kingdoms. Algae and Land plants (embryophytes) are separate Divisions of the Kingdom Plantae. $\endgroup$ – naught101 Nov 11 '15 at 4:08
  • $\begingroup$ @naught101 well, I didn't know that green algae were part of plants, as I learnt it as part of Protists. But other aquatic "plants" are not plants, like kelp is in brown algae which is in Protists. $\endgroup$ – TanMath Nov 11 '15 at 5:11
  • $\begingroup$ Do you have references for your claims? To say that all aquatic plants lack stomata is quite a strong statement. $\endgroup$ – fileunderwater Nov 11 '15 at 20:07
  • $\begingroup$ @fileunderwater: There are semi aquatic plants that ofter have their leaves above water. Those will have stomata. There are properly aquatic "plants", like kelp, but as Tanmath says, they're not embryophytes, so they don't have stomata. $\endgroup$ – naught101 Nov 12 '15 at 9:16

According to the book Stomatal function (Zeiger et al, 1987), many aquatic angiosperm plants have stomata (since they have evolved from terrestial plants), while some have reduced or complete loss of stomata.

However, the book also states that:

...aquatic plants living underwater are devoid of stomata. Leaves that float in water, which are common in ponds, have stomata on their upper surfaces but lack them on the surfaces in contact with water.

  • $\begingroup$ It is true that plants that float on water (hydrophytes) have stomata on one sider, but I think the OP is referring to fully underwater plant-like organisms or plants. $\endgroup$ – TanMath Nov 11 '15 at 19:52
  • $\begingroup$ @TanMath I was merely looking at a couple of sources I know of. As it seems, fully submerged plants indeed often/usually lack stomata. $\endgroup$ – fileunderwater Nov 11 '15 at 20:05
  • $\begingroup$ Oops, I was mistaken when I said hydrophytes float on water. Many hydrophytes are submerged underwater. $\endgroup$ – TanMath Nov 11 '15 at 20:22
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    $\begingroup$ @naught101 Angiosperms like Ceratophyllum submersum (Hornwort) lives fully submerged. I cannot say to what extent their leaves work out of water, but their supporting structures (branches, stems) aren't adapted do life out of water, and cannot support the weight of the plant. $\endgroup$ – fileunderwater Nov 13 '15 at 9:20
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    $\begingroup$ @naught101 I can, from field expierence, tell you that most if not all submerged plant don't survive outside water (incl. Ceratophyllum). The leaves simply dry out. Sometimes they reach up to the water surface, but they rarely protrude more than a few mm. Many species, like potamogeton, myriophyllum, ranunculus do have flowers that grow a few cm above water level. $\endgroup$ – RHA May 24 '18 at 18:59

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