can clover grow under water

If you're talking about the clover you'd find in your yard or a field, no. It will die when submerged. The four-leaf clover that grows underwater is Marsilea sp.
 
The clover that grows in your yard IS of the marsilea family. I dunno if I have heard of anybody trying to convert any though.
 
Yep, some (or perhaps all?) Marsilea species can be grown submerged. They lose the four-leaf clover shape though. It's just one drop-shaped leaf on a stem, and looks similar to glosso.
 
The clover that grows in your yard IS of the marsilea family. I dunno if I have heard of anybody trying to convert any though.

This is not true. True clovers (Trifolium) and shamrocks (Oxalis) are legumes, related to beans and peas. Water four-leafed clover (Marsilea)is actually a fern. They are not at all closely related.
 
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