What do red flowers represent on Mother's Day?

That you remembered Mom. Key Word is red= remember. Actually, each flower has its own meaning where the different colors are concerned

A white carnation, especially on Mother's Day, represents purity for example. A pink carnation means gratitude or "I'll never forget you." A red carnation expresses admiration or could signify my "heart-aches for you" and a purple carnation shows capriciousness. Solid colors say, "yes", while striped carnations say "no" and express a refusal. Sometimes the meanings are conflicting, since striped carnations can, also, mean "sorry I cannot be with you", "I wish I could". A yellow carnation means rejection or "you have disappointed me". Mini carnations mean pure love or "my heart yearns for you". Whatever message you send with a carnation, a splendid aroma will accompany it.