Sentence:  I have more than once sat cross-legged in the grass through a long summer morning and watched without touching while a poppy bud higher than my head slowly but visibly pushed off its cap , <WSD>unfolded</WSD> , and shook out like a banner in the sun its flaming vermilion petals . 
Meaning of the word marked with <WSD> tags:  extend or stretch out to a greater or the full length