How long can a Amazon sword leaf be out of water

How long can a Amazon sword leaf be out of water before it starts dying?. At first a thought its my chemicult thats burning my leaves. but now im thinking i left them without water for too long when i moved them to my PFP tank. they shrivelled (spelling) up within minutes but looked normal once in the water again. but now the edges are starting to die. but all my other plants that never got dry are growing very well.

 

I've seen portions of Swords growing out of the water for periods of days before turning black and shrivelling. On one occasion I've even seen something that looked just like an Amazon Sword being grown as a marginal plant (roots in the water, everything else sticking out).

 

think it mostly depends on the humidity and if the leaves grew themselves out of the water or not....that may sound odd, but will try explain. I've had a sword that stayed nice and small, then started sending out long broad leaves that didn't break the surface, when however my water level dropped and the leaves were directly exposed to the light they started to shrivel. Then it sent out even long leaves that broke through the surface and kept going. The ones touching the lights got a bit dry but rest were fine. Then I moved it outside to a small pond, now all its leaves are out the water, 40-50cm and it flowered and now got about ten mini swords....they started out the water and quickly grew thick leaves that haven't dried up....have some pics i might post soon.

 

swords will happily live as a marginal plant