The chrysanthemums

I think Elisa is guarded at first but the stranger's talk of flowers draws her femininity to the surface. She becomes less constrained. The stranger's feigned interest in her flowers draws Elisa's attention:

"Her eyes shone. She tore off the battered hat and shook out her dark pretty hair. "I'll put them in a flower pot, and you can take them right with you."

Elisa's awakens her emotions by talking to her about her precious chrysanthemums. She, like the flowers, presents her beauty, "Her breast swelled passionately". She is no longer cautious and restrained.