Boy, that site is awful on an iPad. The margins are so wide, it’s like reading a pencil.
I was watching a documentary, awhile back, that said the first flowering plants were underwater plants. I don’t remember the exact age. That indicates that the idea that flowering plants started underwater, isn’t new.
Another fairly recent (geologically) plant, is grass. Whenever you see artistic depictions of dinosaurs, grazing in fields of grass, it’s not really accurate. I think ferns may have filled the “ground cover” niche, back then.
I feel nostalgic when I see formatting complaints, as my defaults on iOS are to put all sites on "reader mode" unless whitelisted. Annoying sometimes but almost never have formatting issues.
Interesting because today the majority of aquatic plants are actually immersed growers, or plants that live part of the season under the water and part out of it. Fully under the water you can find mostly algae.
Paper: https://www.pnas.org/content/112/35/10985. Note that the paper comes to a slightly different conclusion than this summary article: in particular, it never claims that Montsechia might be ‘the original flowering plant’ as the article does, nor does it say that Ceratophyllum is a modern-day descendant of Montsechia (in fact, it says quite the opposite).
How would a flower get pollinated underwater? All of the aquatic plants I can think of float their flowers on the surface for pollination - even eelgrass, which technically flowers underwater (https://www.indefenseofplants.com/blog/2019/8/14/eelgrass-se...)
Seems weird that most (all?) modern aquatic plants lost that ability then. Certainly not impossible by any means, but still weird. Does that mean anything, for example did all/most aquatic plants die off and terrestrial plants move back to the water later?
Aquatic plants have different goals. Most of them are aggressively clonal and flowering is just one possible strategy to compete
For underwater pollination, well, we assume that Posidonia is pollinated by water currents but there is an huge number of things that we still don't know about sea ecosystems.
No offense, but I don't believe you. Can you cite a plant that gets pollinated underwater? Or are you suggesting that this ancient plant also pollinated above the water (as in the case of the eelgrass example I provided)?
OK your obstinance has led me to research this a bit more and I found an answer, Unfortunately it contradicts your (dubious to me) assertion that truly underwater pollination is facilitated by "water currents." Currents affect pollination on the water's surface, but not underwater.
The very, very few plants that are truly pollinated underwater (as opposed to on the water surface) are limited to basically a single genus and here's how it works (it's called hypohydrophily): "The male flowers of Ceratophyllum break and dehisce on the water's surface. Pollen grains sink into the water and come into contact with the stigma, resulting in pollination under water."
