The Rhododendron Species Botanical Garden – An Overview
Steve Hootman
Executive Director of Horticulture & Curator
The Rhododendron Species Botanical Garden, located on 24 acres in Federal Way, Washington, is the premier garden in the world emphasizing the display, collection, conservation, education and research of Rhododendron species. The Rhododendron Species Foundation (RSF), which manages the garden, was founded in 1964 to secure authentic forms of Rhododendron species and to develop a comprehensive collection of this remarkable group of plants. Since then, the RSBG has developed into a Pacific Northwest institution, a major tourist destination, a conservation collection, a horticultural mecca of international repute, and a "must-see" visit on any West Coast garden tour. The RSBG disseminates information, provides resources, works toward conserving ecosystems, and actively pursues the preservation of rare and endangered Rhododendron species. Furthermore, the RSBG supports a broad and diverse membership bonded by a love of these plants and a desire to share both plants and information with fellow gardening enthusiasts, other conservation-based organizations and scientific institutions.
History and Support
The RSBG is supported by a not-for-profit 501 (c) (3) charitable organization, the Rhododendron Species Foundation, founded and incorporated in the state of Oregon in 1964 to secure the finest authentic forms of Rhododendron species. This was an important goal and mission because at that time in North America, properly named and authentic species rhododendrons were very rarely available to gardeners, collectors or public botanical gardens. In the intervening years, the RSF greatly expanded its scope, its programs and its international outreach. It now functions as a completely independent, conservation-based organization that has shifted its primary focus to the promotion of education, research and the conservation of Rhododendron species through ex situ and in situ means and methods.
In 1975, the garden moved to its present location in Federal Way, Washington. Endowment funds started in 1974 and currently totaling approximately $9M help support the garden and its public, conservation and research activities. Income from these funds, combined with annual plant sales, garden admissions, memberships, grants, and gifts from members, support the RSF with an annual budget of about $1.3M.
Organizational Structure
The RSF is governed by a board of 40 members, including nine officers, and managed jointly by the Executive Director of Horticulture & Curator and the Executive Director of Business Operations with a staff of six full-time and two part-time employees. On average, between 40 and 50 volunteers contribute approximately 5500 hours each year. Committees are responsible for activities including publications, membership recruitment, planning, endowments and investments, research and public education. This active set of services benefits the membership (1300 members worldwide), the public interested in conservation and cultivation of the genus Rhododendron, and the scientific, botanical and horticultural communities.
The Collection
The Rhododendron Species Botanical Garden is recognized internationally as the finest and most complete collection of documented Rhododendron species. The collection includes thousands of accessions (individual clones) grown from wild provenance material as well as horticulturally superior and named forms selected from gardens and nurseries around the world. Our goal is to represent each taxon as completely as possible given the various obvious constraints. This provides us with the chance to preserve as much of the genome and to display as much of the natural variation within each species that we can physically and economically manage. For example, the species R. rex subsp. rex is represented in the collection by approximately 70 distinct individual plants grown from a dozen or so wild collections made throughout the natural range of that species.
The Rhododendron collection currently holds an estimated 900 of the 1200 or so taxa in the genus. The vast majority of the missing taxa in our collection are within the tropical (vireya) subsections. This scientifically documented and selected material is made available to scientists, collectors and gardeners for use in scientific studies, breeding programs, conservation programs and for public education and beautification in cities, gardens and parks around the world. We also screen for, and select, horticulturally superior forms of wild species rhododendrons for garden use and landscaping.
Display
Our twenty-two acres of display garden are open to the public six days a week. About 10,000 Rhododendron plants from every natural habitat in the world are displayed with their companion plants. These non-rhododendron accessions are those plants found growing naturally with Rhododendron species in their native habitats. The blooming season extends year-round. From the diminutive alpine species to the giant big-leaved forest rhododendrons, the display is astonishing in showing the diversity of habit, leaf structure, and flower shape and color of these outstanding plants. Notable at the RSBG is the Rutherford Conservatory, home to tropical rhododendrons and companion plants from tropical mountain zones. This beautiful display conservatory provides year-round interest to visitors and serves as a research resource for scientific study of this tender and increasingly threatened group of plants, the vireya rhododendrons.
One of the most eminent horticulturists in the world proclaimed the RSBG as “one of the top five botanical gardens in the country”..."I think your botanic garden is one of the gems of the art in North America"… (Panayoti Kelaidis, Scientific Curator, Denver Botanic Gardens, 2012)
Conservation
The centers of diversity for the genus Rhododendron are in eastern Asia and the tropical islands on the shared border of the Indian and Pacific Oceans. The incredible biodiversity in these densely populated regions is under extreme pressure, with loss of natural habitats proceeding at an alarming rate. The RSBG is the world’s largest ex situRhododendron conservation collection, with the long-term goal of the preservation of genetic material for educational and scientific studies and possible restoration of threatened or exterminated species to their countries of origin. The garden also cultivates and conserves those plants found growing with rhododendrons in their wild habitats, providing an additional educational experience relating to biological communities and their composition.
We are currently working on establishing Memorandums of Understanding with various international organizations to facilitate the research and conservation of endangered Rhododendron taxa. Among these are the Kunming Institute of Botany, Yunnan China, and Hanoi University in Vietnam.
In collaboration with other scientific and conservation-based organizations, we have developed a series of satellite collections in those botanical institutions based in climates that differ from our climate in the Pacific Northwest. Institutions such as San Francisco Botanic Garden, Sonoma Botanic Garden, UC Berkeley Botanical Garden, and the Humboldt Botanic Garden all have substantial holdings of RSBG accessioned plant material. This material is monitored, evaluated and exchanged with other institutions and forms a backup collection for those taxa which would not otherwise survive outdoor cultivation in western Washington.
Research
World-renowned scientists from University of Washington, University of Wisconsin, University of Virginia, the USDA, Harvard, Massey University in New Zealand and many others have used this extensive and scientifically documented collection for research into the genetics, biochemistry and evolution of this large group of botanically important plants. We provide documented material to universities and scientists around the world. This material is of prime importance in ongoing phylogenetic and phylogeographic studies. And, in partnership with the University of Washington, we participated and contributed to the sequencing of the entire genome of the genus Rhododendron.
We are actively engaged in ongoing studies of native Rhododendron populations and support efforts to conserve the ecosystems supporting these populations. We are also actively involved in and supportive of, exploration for new and rare rhododendrons in the wild and their documentation. Another of our primary functions is the preservation of wild species through propagation and distribution, disseminating scientifically documented living material to horticulturists, breeders and researchers around the world. In addition, as one of the primary resources relating to all things Rhododendron species, we provide assistance to other botanical gardens and related institutions relating to the proper identification, nomenclature, taxonomy and cultivation of the plants in their collections.
Ongoing research projects by the RSBG staff includes field work on the taxonomic status of the members of subsection Fortunea. When the revision of the genus Rhododendron was published by the Royal Botanic Garden Edinburgh in the early 1980s, there were 18 known species in subsection Fortunea including such well-known taxa as sutchuenense, calophytum, fortunei, decorum and griffithianum. With ongoing exploration and research, at the current time we are looking at more than 32 taxa in this highly ornamental subsection. Thanks in large part to the efforts of the RSBG and our associates, we have been able to sort out and correct the taxonomy of several taxa in this confusing group including yuefengense/yuanbaoshanense, cardiobasis, polytrichum/chihsinianum, qiaojiaense/nymphaeoides, jingangshanicum, xiaoxidongense, etc. - all of which were relatively unknown until recently and many of which were incorrectly categorized taxonomically.
Another very interesting study we are currently undertaking is trying to establish the history and relationships between three possibly different taxa in three widely disjunct populations in China and Vietnam. The Vietnamese taxon is still known only from a single observation and is undescribed. However, it appears to be an ancient, isolated relict probably most closely related to R. dachengense/scopulorum in eastern Guangxi Province, China. This latter taxon is itself poorly known and little studied but has been placed in subsection Taliensia by Chinese botanists.
This seems highly unlikely or at least highly unusual considering the geographical location and low altitude where it occurs. The third entity is the species R. zhangjiajieense known from only a small area in northwestern Hunan Province which has also been placed in subsection Taliensia by Chinese botanists. All three have very similar descriptions and morphological characteristics, including a very thick and wooly indumentum - very unusual in these particular regions of China/Vietnam. What is especially interesting is that all three of these taxa survive in relict floras in extremely limited populations in almost the exact same habitats (vertical sandstone cliffs) and elevations, but each of them is widely disjunct physically. Are these three taxa closely related? The same thing? How have they survived in such limited and specific habitats? What are they related to and what are they derived from? Are these small and fading, isolated populations the relict ancestors of our current, modern species? So many questions, and all this from just three taxa in this huge genus of around 1200 species.
Education
Education has always been a primary goal of the RSF. As early as 1985, the RSBG organized an international Rhododendron Species Symposium held in Tacoma, Washington. Another long-held educational practice of the RSBG is to provide horticultural students with practical hands-on experience. The student intern program was inaugurated in 1986. Since that time, well over 100 budding horticulturists have worked and studied in the garden and nursery. Education outreach to RSBG members and the general public is also important. The RSBG is actively involved in the publication of both popular and scholarly articles and provides lectures and classes around the world.
In 2006 the RSBG published the first edition of its own annual journal – Rhododendron Species. The intent of this journal was to provide a technical reference volume for serious students of rhododendrons that would also serve as an informative guide for general gardeners and collectors. This journal has been received with considerable enthusiasm. This volume also provides an incentive for membership in the RSBG and gives the organization additional international stature and authority.
As we continue to grow and develop as an institution, we continue to marvel at, and learn from, the beauty, diversity and mystery of the genus Rhododendron.
RSF Mission
Founded in 1964, the RSF is dedicated to the conservation, research, acquisition, evaluation, cultivation, public display and distribution of Rhododendron species; provides education relating to the genus; and serves as a unique resource to scientific, horticultural and education communities worldwide. To achieve this mission we will:
Acquire and maintain a comprehensive collection of Rhododendron species
Conserve Rhododendron species through the cultivation and distribution of selected forms and documented wild collected materialSupport the Rhododendron Species Botanical Garden, a living museum, for the display and cultivation of Rhododendron species
Provide information, education, and support research for persons interested in the genus Rhododendron
~ Thank you to Alan Campbell for submission of this article