A lot of plants need well drained soil. They're said to not like getting their feet wet. The explanation given is that the root need oxygen and will die and rot if they're in standing water for too long.
But a lot of the same plants will root if you take a cutting and put it in water for long enough.
An example of this is kiwi vines. They require well drained soil. But their cuttings will root if you put them in a cup of water for a few weeks. I'm doing this right now (for the first time), mine have just began growing roots.
I've also grown a sweet potato in coffee cup filled with water.
So, why does this work? Why don't cutting drown instead of grow roots, and why to the roots continue to grow instead of immediately rotting and dying, since they don't have any oxygen?