An Iris flower has 6 petals, three of which stand upright in the middle of the flower and three that grow out horizontally with tips which fall backwards. The fleur-de-lis symbol is actually a stylised iris flower.
On Iris Day, 10 things you might not know about irises:
https://topicaltens.blogspot.com/2015/05/8th-may-iris-day.html