In my humble opinion, the prototype for the style is Widmer Hefe because Widmer was the first brewery to brew an American Wheat beer. Widmer started with an alt strain from Zum Uerige, which is held under the Wyeast accession number 1007. The strain became less flocculent in use at Widmer. The less flocculent version is held under the Wyeast accession number 1010. If I recall correctly, Widmer Hefe used to be bittered with Willamete and finished with Cascade, which gave it the citrus brightness. We are talking about a restrained hopping rate here. The grist is basically 2-row pale, malted wheat, and a small percentage of crystal/caramel.