The mustard plant belongs to the family Brassicaceae, and its floral formula is:
\[
Ebr Ebrl \oplus ♂ ♀ K_{2+2} C_4 A_{2+4} \overline{G} (2)
\]
Explanation: Ebr Ebrl: Ebracteate and ebracteolate \(\oplus\): Actinomorphic ♂ ♀: Bisexual \(K_{2+2}\): Calyx with four sepals arranged in two pairs \(C_4\): Corolla with four petals \(A_{2+4}\): Six stamens (tetradynamous) \(\overline{G} (2)\): Superior ovary, bicarpellary