In a complete sentence try to state the story's theme? Why are Elisa's chrysanthemums so important to this story?
Elisa's chrysanthemums are the only things that give her life meaning, but when the unscrupulous traveling tinker throws them away on the road it is as if he is negating her reason for living.
The big flowers she cultivates with so much work and care provide the only beauty in her drab, monotonous existence. They afford an outlet for her creativity and for her feminine nurturing instinct. They give her something to love and seem to love her in return. And furthermore, they are her only claim to fame in this entire region. She has a genius for raising plants--but the only plants the men care about are edible ones that can be sold for cash. They raise cattle only to sell them to be slaughtered. They can't understand why anyone would devote so much time and attention to raising gaudy flowers that have no retail value but are only objects of beauty.
The tinker is worse than any of the other men because he only starts the conversation about the flowers in order to establish a cordial relationship with Elisa which will lead to her giving him a little work to do to earn a little money. He is cagey. He understands human nature, and he understands these farm wives who all lead such dreary lives from Seattle to San Diego. When she sees that he has thrown her chrysanthemum shoots out on the road, she not only feels violated but feels the emptiness and futility of her whole existence. The man regards the plants as worthless and only keeps the pot because it has a tiny bit of monetary value. There was no other woman who wanted him to bring her chrysanthemum shoots. He told Elias a deliberate lie.