  Grammic monoids have recently been introduced by Christian Choffrut in terms
of the action of the free monoid over a fixed ordered alphabet $X$ on the set
of rows of Young tableaux filled with elements from $X$ via Schensted's
insertion. For $X=\{a,b,c\}$ with $a<b<c$, Choffrut has identified the grammic
monoid on $X$ with the quotient of the plactic monoid on $X$ over the
congruence generated by the pair $(bacb,cbab)$. Since $cbab\ne bcab$ in the
latter monoid, the quotient is proper. We show that, nevertheless, the plactic
and the grammic monoids with three generators satisfy the same identities.
