Historical Rules · 18 June 2010
Rule 305.6
Official source text from the 18 June 2010 Rules release
The basic land types are Plains, Island, Swamp, Mountain, and Forest. If an object uses the words "basic land type," it's referring to one of these subtypes. A basic land type implies an intrinsic ability to produce colored mana. (See rule 605, "Mana Abilities.") An object with a basic land type is treated as if its text box included "{T}: Add [mana symbol] to your mana pool," even if the text box doesn't actually contain text or the object has no text box. Plains produce white mana; Islands, blue; Swamps, black; Mountains, red; and Forests, green.