Classic O'Keeffe subject
I believe the answer is:
lilies
(Other definitions for lilies that I've seen before include "Plants with showy pendulous flowers" , "Luke: ` `Behold the ...... of the field' '" , "'''Consider the ... of the field, how they grow'' (Bible) (6)'" , "Flowering plants" , "Plants with slender stems and large trumpet-shaped flowers" .)