To confirm the registration of an Australian native hybrid & view its composition/progeny: (Database as at 1st January 2020 RHS registrations)
For non-Australian Dendrobium hybrids use the Dendrobium Hybrids checklist here
Sarco. Madge= hartmannii x Snowhart ( has 7 hybrid progeny ) registered: 30/10/2007 by Roper N.
Species composition summary:
Sarco. Madge = hartmannii x Snowhart = hartmannii x [Cherie Snow x hartmannii]
Cherie Snow = Cherie x hartmannii = [Fitzhart x fitzgeraldii] x hartmannii
Fitzhart = hartmannii x fitzgeraldii