closeup view of a blue water lily.

africa ancient anoxic aquatic arabia autumn blossom blue botanical caerulea causing civilization closeup conditions daisy deeper dominant eastern egyptian flower found freshwater genus green grown habitats herb human lakes leaf lily meadow mud naturally nature nouchali nutritionally nymphaea ornamental parts pathogen petal plant pools poor produce regions religion rivers roots schistosomiasis shrub significance snail southern species spread sunlight tolerate var variety view water wildflower yellow