The quote about the flame tree,

"I tried hard but I could not keep my eyes from straying to the flame trees, their blossoms tumbling in the wind of the coming storm",

is found on page 47 in my book, the 1995 Penguin edition, but page numbers do vary from publisher to publisher.  It would probably be more helpful for me to tell you that the quote is in the first half of Chapter 4, the last line of the third section of that chapter.

A few paragraphs earlier, there is a related reference to "the flamboyants...in full bloom...brilliant red flames lit in every tree...and beyond, some threatening thunderclouds". The author uses the metaphor of flowers to symbolize women - especially the Mirabal women, and in this instance, Patria in particular.  She is recalling just having turned sixteen and entering the "full bloom" of life.  The "threatening thunderclouds" in the background of the blossoming flame tree is a warning of great trials to come, and, in the previously mentioned quotation, the "blossoms tumbling in the wind of the coming storm" foreshadow that the sisters will not survive the troubles with which they will be faced (Chapter 4).