well, i checked, and neither Verte nor Verde is a registered trademark......so, legally, there's nothing Verte can do to stop Verde from using their mark. If Verte were to register its mark, then they could sue Volcom for the used of Verde....because both the meaning of the words and the logo themselves are substantially similar and could cause confusion with consumers.
so, if Verte is actually serious about it, they should register their mark and go after Volcom......the only problem is that Verte probably doesnt sell enough product to show any sort of "damages" due to Volcom's use of the Verde line....the best they could do is to try for an injunction.
but im sure just writing nasty notes on the internet is satisfaction enough