  It is shown that Suzuki-Ree groups can be easily defined by means of
comparing two fundamental representations of the ambient Chevalley group in
characteristic 2 or 3. This eliminates the distinction between the Suzuki-Ree
groups over perfect and imperfect fields and gives a natural definition for the
analogues of such groups over commutative rings. As an application of the same
idea, we explicitly construct a pair of polynomial maps between the groups of
types B_n and C_n in characteristic 2 that compose to the Frobenius
endomorphism. This, in turn, provides a simple definition for the Tits mixed
groups over rings.
