Presumably members of the Hegg family (daughters of Franz Hegg), Norway. The Hegg family were partners of the Ecke Ranch in Europe for plant licensing.
Transcription on back: "To Paul Ecke Poinsettias with sincere appreciation for your gifts of beautiful plants which added so much to our traditional holiday telecasts. Christmas 1981." Unknown signatures
Personal letter from Dinah Shore to Paul Ecke Jr. thanking him for holiday poinsettias. Dinah Shore was a singer and television personality, and host of the Dinah Shore Show.