How do underwater flowers function?

[Milliardo Peacecraft]

As I was sitting looking at my aquarium last night, a thought occurred to me.  How do underwater flowers function biologically.  I have a working understanding of how flowers grown out of the water function.  Pollinators are attracted to the pollen/nectar and it is then passed from plant to plant thus generating seeds, which is the ultimate goal of the flower/plant.  How does this function for underwater plants.  Does it just release stuff into the water column and it eventually finds other plants, does it hope other critters spread it, or is it something totally different.  I was wondering if any of you have ever thought about that before and maybe had more insight.  I realized last night that I have never really thought about that before.

I know I could probably just go to Google and read a few articles and get an answer, but sometimes it's more interesting to contemplate about it for a while thinking about how everything works and then think about it with others.  The process of discovery is sometimes more fulfilling and interesting of a journey than the answer is.

[JettsPapa]

I haven't googled the answer either, and I'm not a botanist, so this is just an old man speculating.  It's my understanding that most of the plants we grow fully under water in our aquariums grow differently in the wild, where they protrude out of the water at least part of the year.  I suspect that's when their flowers function to create and fertilize seeds.

[Sarina]

Well, underwater plants may flower, but that is not usually how they reproduce because they function essentially the same as plants that grow above water. Most aquatic plants available in the aquarium trade are created by tissue culture cloning. This is a method of taking a tiny sample of a plant and placing it in a sterile environment with lots of hormones that cause the plant to create clones of itself. You can purchase these plants in their tissue culture form in sealed cups, or you can buy them as adult plants after they have been removed from the tissue culture and have grown out to their full size. Usually this happens in large greenhouses in hydroponics systems, with the foliage out of the water for faster growth and less algae management. 

Most house plants are created this way, as well, which is why there are some aroids (like types of pothos) that do not flower at all anymore. These plants can really only be created by cloning. 

Tissue culture cloning is one of the fastest, cheapest, and most energy efficient way to cultivate new plants. It is also one of the reasons that so many variegated plants exist. Variegation occurs when a genetic mutation causes portions of the plant to lack chlorophyll, or have variables in chlorophyll that can display varying shades of green, yellow, cream, and white. Plant genetics are a whole deep dive waiting to happen, so I won't get too nerdy on you, but essentially very few plants are cultivated from seeds these days. 

In the wild, a lot of plants reproduce by cloning, as well. Any plant that creates pups is essentially cloning itself, which is what a lot of crypts, swords, and grasses tend to do. Even plants like anubias will create pups that will then break off and reattach to a different location depending on water flow. Plants that have a chance to flower above the water line may produce seeds, but germination can be difficult if the environment is not quite right or there aren't enough pollinators to create viable seeds. In short, flowering is only one way that a plant can reproduce, and it isn't always the most reliable. 

[Milliardo Peacecraft]

@Sarina . Thank you!  That is an awesome reply.  It's amazing that plants will utilize multiple methods of reproducing themselves to insure survival.

[Sarina]

@Milliardo Peacecraft I know! I study this stuff in my free time because I find it so fascinating. Plants are truly incredible 😊

[Pepere]

But I was hoping the flowers produced a nectar appealing to fishies and they pollinated them….

Wouldn’t it be great if Bumblebee Platys did this?

Edited July 18 by Pepere

[Seattle_Aquarist]

Hi All,

I can think of a  couple of species that form flowers underwater which then self-fertilize and form seed pods with viable seeds,  The pods split open spreading seeds throughout the tank.  After a period of time those seeds germinate and form plantlets.  The two species that come to mind are Nymphaea minima and Barclaya longifolia.  Here are some plantlets of Barclaya longifolia that sprouted in my 75 gallon and I moved to a 10 gallon 'nursery tank'.  The pot you see in the tank was an experiment to see if the Barclaya would grow better with ADA Amazonia covered with sand or just sand.....just sand worked as well as ADA with sand covering.  -Roy

10 gallon with Barclaya longifolia plantlets

Edited July 19 by Seattle_Aquarist