JARS v41n1 - Maximizing Genetic Variability: The Rhododendron Species Foundation Seed Program

Maximizing Genetic Variability: The Rhododendron Species Foundation Seed Program
Richard V. Piacentini, Director
Rhododendron Species Foundation
Federal Way, Washington

Many of the plants originally selected and accessioned in the Rhododendron Species Foundation (RSF) collection came from notable gardens in Great Britain. There as in the Pacific Northwest hardiness to heat and cold is not as critical a concern as it is to rhododendron growers in other parts of the United States. For this and other reasons the RSF collection has not stressed the hardy clones of species. Other reasons include; (1) the limited resources at the RSF to develop new clones; (2) lack of wild-collected seed since the closing of China in the 1950's and (3) limited growing and experimentation by growers in harsh climates, most notably due to limited availability of new genetic material. Two recent changes should reverse this situation. First, the reopening of China has allowed wild-collected seed from this vast storehouse of rhododendrons to find its way to the United States. Second, the unanimous approval of the RSF Board at their October 1986 meeting for an RSF Seed Program.
The new seed program will enable Foundation members to aid the RSF in making new selections and new introductions. It will also allow the RSF to provide its members with opportunity to experiment with the extensive genetic potential that exists in the genus. There are still many species in cultivation that are representative from limited wild populations and there are those still limited by their difficulty in propagation.
Seed in the program will come from two sources; verified wild-collected seed and controlled hand-pollinated intraspecific crosses (within the same species) of documented clones growing in the RSF Collection. One major area to be emphasized in RSF produced seed will be selection for hardier forms and borderline hardy forms (i.e. NE, SE, Midwest U.S.) from which fully hardy selections can be made. We hope many of our members outside the Puget Sound area will participate in this program so that new clones can be grown and tested in more rigorous climates and in climates in which they may ultimately be more widely grown. It will take time to actually see the fruit of our collective labors but ultimately we expect such a program to expand the range of clones and species able to be grown in other parts of the United States.
Participants in this seed program must realize that there is no guarantee of superiority of rhododendron produced from seed. It is the nature of seed that there will always be many undesirable forms, from a growers point of view, as well as desirable forms. But the potential for greatness remains and it is very likely that many fine forms remain to be discovered. The Foundation cannot guarantee the authenticity and superiority of seed and will not award such seed an authentic RSF number. Every effort will be made by the Foundation to ensure the authenticity of seed, however those wishing authentic documented species should limit their growing to RSF documented and and numbered plants. Members interested in intraspecific hybrid seed (between different species) can produce their own from custom collected pollen through the RSF Pollen Program.
The seed program is essentially a pilot program by the RSF, we have not had such a program previously. The program will be entirely volunteer run under the direction of staff and the strictest guidelines will be developed and followed through all stages from seed production to growing. Since the Foundation does not have satellite gardens in different climates we will be relying on our members to act as an extension of the RSF. Because of the commitment asked of growers and the initial limited supply of seed, only individual members of the RSF will be asked to participate. ARS chapter members, non-members, and those not wishing to follow RSF procedures may obtain surplus seed from the ARS Seed Exchange. The RSF has agreed to provide the ARS Seed Exchange with all surplus wild collected and RSF produced seed. If demand for seed from members and the ARS Seed Exchange warrants it the program will be expanded to meet such a demand. Whether an individual chooses to participate in this program or not, we expect the range of species hardy in other areas to ultimately increase for the benefit of all.
With the help and support of members and many ARS chapters the RSF has developed one of the most extensive species collections in existence. It is important to reflect for a moment on the major reason for the formation of the Foundation and for the support of its members. In the early 1960's very few true rhododendron species were available in this country. Collectors were limited to raising species from seed. More often than not the seed they received was from open pollinated sources and was unrepresentative of the species. Today, with many documented species now available through the RSF Distribution Program and other sources we feel that it is time to offer seed from a carefully run program and unlock the tremendous genetic potential and variability that exists within the RSF collection and the wild.