There was a certain expression in chapter 8 of the novel, which I can not figure out, that is "Fight for it with dusty miller."
To provide a context I will copy the respective passage from Dracula:
"Lucy was really tired, and we intended to creep off to bed as soon as we could. The young curate came in, however, and Mrs. Westenra asked him to stay for supper. Lucy and I had both a fight for it with the dusty miller. I know it was a hard fight on my part, and I am quite heroic. I think that some day the bishops must get together and see about breeding up a new class of curates, who don't take supper, no matter how hard they may be pressed to, and who will know when girls are tired."
What can "fight it with the dusty miller" mean in the context above?
Your help is much appreciated.