Historical Rules · 17 June 2011
Rule 204.3c
Official source text from the 17 June 2011 Rules release
If a card with multiple card types has one or more subtypes, each subtype is correlated to its appropriate card type. Example: Dryad Arbor's type line says "Land Creature -- Forest Dryad." Forest is a land type, and Dryad is a creature type.