Complex sentence: Mutants are viable, but may be distinguished from normal plants by FeCl3 staining: plants able to synthesize benzoxinoids have pale blue color when crushed and treated with FeCl3 solutions.
Split into simpler sentences: Mutants are viable, but may be distinguished by FeCl3 staining from normal plants. Plants able to synthesize benzoxinoids have pale blue color when crushed and treated with FeCl3 solutions.