This paper shows that the
highest weights of the K-types of any irreducible admissible representation of
SU(1,n) are determined by certain restriction maps from u to u ∩ k cohomology. In
particular, the image of these maps determines a set of points in a Cartan
subalgebra. It is proved that the highest weights of the K-types are given by
intersecting a translate of the root lattice with the closed convex hull of the points
determined by the restriction maps.