I have no personal knowledge of this individual, but I did a quick Google search and came up with the following site:
which yielded the following:
Hans P. Sass, Daylily Breeder
Stout Silver Medal
The highest award a cultivar can receive is the Stout Silver Medal, given in memory of Dr. Arlow Burdette Stout, who is considered to be the father of modern daylily breeding in North America.
This annual award--as voted by AHS Garden judges--can be given only to a cultivar that has first received the Award of Merit not less than two years previously.
Hans P Sass won the Stout Silver Medal for two varieties. Few daylily breeders have done this well.
1950 HESPERUS (Sass 1940)
1953 REVOLUTE (Sass 1944)
Hemerocallis varieties attributed to H. P. Sass:
Dorothy McDade H. P. Sass 1941
Hesperus H. P. Sass 1940
Midwest Majesty H. P. Sass 1949
Moonbeam H. P. Sass 1940
Nebraska H. P. Sass 1940
Orange Beauty H. P. Sass 1945
Revolute H. P. Sass 1944
Another site showed this picture, may have been taken in 1950. It appears that he was even better known for hybridizing iris.
Hope this helps.