  We study affine Grassmannians for ramified triality groups. These groups are
of type ${}^3D_4$, so they are forms of the orthogonal or the spin groups in 8
variables. They can be given as automorphisms of certain twisted composition
algebras obtained from the octonion algebra. Using these composition algebras,
we give descriptions of the affine Grassmannians for these triality groups as
functors classifying suitable lattices in a fixed space.
