"Roses....no special significance." I agree entirely, I was mainly trying to show that May Day has long featured the Maypole in America. Roses were often used because there are many early varieties and they are colorful and large. Whatever significance the custom had, it was just a case of "The flowers that bloom in the Spring, Tra-la," the love of the good weather and a chance to get together to celebrate and have outdoor picnics and all that. Organizers of May Day had to have a theme, and something for people to participate in. The observance might become ritualized, but no one worried about significance.