This would be a better contribution if I could remember where I read it, but I understood that young people of both sexes sometimes wore laurel or other greenery as a sign of constancy to an absent lover. Whic, if they hadn't yet slept together, would amount to a sign of virginity. I suppose it would have served to warn other suitors to keep their distance. The custom may have its origin in classical mytholgy, as explained in other posts.

It comes in the English traditional song "Sheep Crook, Black Dog": "I'll lay o'er the green branches although I am young.." (this sung by a male); and also: "Fine laurels, fine laurels, you've proved all unkind".