Rose

"And Rezia came in, with her flowers, and walked accross the room, and put the roses in a vase, upon which the sun struck directly, and it went laughing, leaping around the room. She had to buy the roses Rezia said, from a poor man in the street. But they were almost dead already, she said, arranging the roses.

So there was a man outside; Evans presumably; and the roses, which Rezia said were half dead, had been picked by him in the fields of Greece. "Communication is health; communication is happiness; communication-" (Pg 93)

The picked roses represent Septimus and his struggle. He was picked by Evans, a dear friend who basically transformed his entire life in the war. After Evans died, presumably to something with communication in Greece (which was a very big issue in World War I), Septimus loses his internal feelings. It is described that he felt little sadness for his friend. The lack of emotions symbolize the half dead roses that Rezia had bought from the poor man. Just as the roses were placed inside a vase, Septimus is being contained by society and the doctors who try to help him. Roses eventually fade after being picked, no matter the method in preserving it; likewise, Septimus' death symbolizes the fading of the rose in the vase.