Two beauties that share a problem

My planned post for today was thwarted by weather, with rain making it impossible to get the final "after" photo needed after a little digging project -- maybe my first of the year? Anyway, I instead noticed that a couple of potted plants have quietly become gorgeous, but they share a problem. First, the beautiful part...

...starting with this "umbrella palm" (Cyperus alternifolius) or at least that's what I think it is. I rescued it a few years back from a friend's compost pile and he didn't know the exact name.

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Although this plant loves water, it is also very hardy -- it had been on his compost pile for a couple of weeks he said, but it quickly sprang to life after I planted it up. This is the first year that I've given it this much root space, usually growing it in a smaller pot.

Isn't it wonderful?

My other beauty is related, Cyperus papyrus:

This one got a late start this year so is not as full as it has been in the past, but it's still so satisfying!

The problem that both of them share is drooping stems.

Is this a sign of too little water? Too little sun? Something else?

The umbrella palm does it too, although it's harder to see because of the other pots:

I do know that these plants use this as a form of propagation, as the heads that droop into the water will form new plants, but I've also seen specimens that are completely upright so it doesn't always happen.

Does anybody know what's causing this?

(Maybe it's just heavy rains bending them down and they are unable to pull themselves back up?)

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