| The American Hosta
Society |
| American Rose Society |
| American Hemerocallis Society |
| American Horticultural
Society |
| American Rhododendron
Society |
| Azalea Society of
America |
| Brooklyn Botanic Garden |
Calus Canna Collection
- Poland
|
| Hardy Plant Society Mid
Atlantic Group |
| Hosta Library |
| International
Water Lily and Water Gardening Society |
| Maryland Native
Plant Society |
| North American Native
Plant Society |
| North American Rock
Garden Society |
| Philadelphia
Rose Society |
| Sedum
Society |
| St
Andrews Botanic Garden |
| The American
Conifer Society |
| The
Herb Society of America |
| The Nature
Conservancy of Pennsylvania |
| The Royal Horticultural
Society |
| The Royal Botanic Garden
Edinburgh |
...Natura, artis
magistra