Eschscholzia.
Easter Lily
iris
I Only Know One flower which is The "Xella"
a flower that starts with N is NARCISSUS
TULIP
tulip
aster
freesia
The grass flower generally have leafy bracts (lemma & palea), hence form a simple flower.
A flower that starts with the letter "U" is Ursinia, a bright and attractive flowering plant. I recently came across this flower while reading flower guides from local florists such as Sai Flower and other gardening resources.
Azalea is a showy flower. It begins with the letter a.
In that sentence, "flower" is the simple subject.