Does colorless mana produced by a land with a non-green mana symbol affect its color identity in Commander?

In Commander, a card's color identity is determined by every mana symbol that appears anywhere on the card — in its mana cost, rules text, or anywhere else it is printed (CR 903.4). This includes mana symbols in activated abilities, triggered abilities, and reminder text.

Colorless mana (represented by {C}) has no color and does not add any color to a card's identity. However, if a land has an ability that costs or references a colored mana symbol — for example, an activation cost like {G} — that symbol contributes to the card's color identity regardless of what mana the ability actually produces.

The key rule is CR 903.4: 'A card's color identity is its color plus the color of any mana symbols in the card's rules text.' The color of the symbol matters, not the color of the mana produced by the effect.

Concrete example: Suppose a land has the ability '{G}: Add {C}{C}.' Even though the ability only produces colorless mana, the {G} symbol in the activation cost gives the land a green color identity. It could only be included in a Commander deck whose commander has green in its color identity.

If a land only produces colorless mana and has no colored mana symbols anywhere on the card (e.g., Wastes or most basic utility lands), its color identity is colorless and it can go in any Commander deck (CR 903.5b).