oops! sorry for making one no one could get!
Jubal was close in getting a flower, but the answer is actually a blue lotus
In the old tales = Egyptian and Greek mythology
the rising sun= the Egyptians used the open blue lotus as a symbol for the rising sun
guardian of the place of life= blue lotus growing in the Nile, which the ancient Egyptians thought of as a place of magical life/ressureation, as well as a literal life source
gentle days and nights= a reference to the lotus eaters of Greek myth, the blue lotus has soporific properties
...and the joke is based around the idea that if you tried to sit under a water lily (of any kind) you'd drown
...I think I just proved I'm too much of an Egyptology nerd to function, oh well