XMLLiterals and language

In my application I often deal with XHTML in literal values. The literal 
have a language as a whole, usually this is the language of all the 
xhtml elements but not necessarily. Currently I'm storing these as plain 
literals, now I read in rdf-concepts that XMLLiterals have a root 
element "rdf-wrapper" which may have an xml:lang. Do I understand this 
right that all xml-literals have this (implicit) wrapper and may have a 
language? How do I encode an XMLLiteral with language in rdf/xml?

The RDF-Validator does not mention the language in the triple-list 
generated from the following:

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:dc="http://purl.org/dc/elements/1.1/">
  <rdf:Description rdf:about="http://www.w3.org/">
    <dc:title  rdf:parseType="Literal" xml:lang="en">World Wide Web 
Consortium</dc:title>
  </rdf:Description>
</rdf:RDF>

Thanks!
reto