Sure, you may.
903.4. The Commander variant makes use of colour identification to find out what playing cards could be in a deck with a sure commander. The colour identification of a card is the colour or colours of any mana symbols in that card’s mana price or guidelines textual content, plus any colours outlined by its characteristic-defining skills (see rule 604.3) or colour indicator (see rule 204).
The phrase “Plains” isn’t a mana image, and despite the fact that that card itself has an implicit (T): Add one white mana, it would not seem in Brokers Hideout rule textual content. And for completeness, it would not have an effect on the 2 different talked about guidelines both:
604.3. Some static skills are characteristic-defining skills. A characteristic-defining capability conveys details about an object’s traits that might usually be discovered elsewhere on that object (corresponding to in its mana price, kind line, or energy/toughness field). Attribute-defining skills can add to or override data discovered elsewhere on that object. Attribute-defining skills operate in all zones. Additionally they operate exterior the sport and earlier than the sport begins.
204.1. The colour indicator is printed to the left of the kind line straight beneath the illustration. It consists of a round image crammed in with a number of colours. A colour indicator is often discovered on nonland playing cards with out a mana price.
204.2. An object with a colour indicator is every colour denoted by that colour indicator.
