In Marigolds, How does this section hint at becoming an adult?

"Whenever the memory of those marigolds flashes across my mind, a strange nostalgia comes with it and remains long after the picture has faded. I feel again the chaotic emotions of adolescence, illusive as smoke, yet as real as the potted geranium before me now. Joy and rage and wild animal gladness and shame become tangled together in the multicolored skein of 14-going-on-15 as I recall that devastating moment when I was suddenly more woman than child, years ago in Miss Lottie’s yard. I think of those marigolds at the strangest times; I remember them vividly now as I desperately pass away the time waiting for you, who will not come."