JARS 42n3 - Vireya Rhododendrons At Lyon Arboretum

Vireya Rhododendrons At Lyon Arboretum
Robert Hirano
University of Hawaii
Honolulu, Hawaii

The Harold L. Lyon Arboretum is an organized research unit of the University of Hawaii at Manoa dedicated to research, education and public service as related to its unique resources. The 124 acre site is located in Manoa Valley on the island of Oahu, four and a half miles inland from Waikiki. Typically the environment is one of a tropical rainforest, averaging approximately 165 inches of rainfall per year. Elevation ranges from 425 feet along its lower boundary to about 2,000 feet along the ridge tops of the Ko'olau Mountains, its upper boundary.

Lyon Arboretum
Lyon Arboretum
Photo by Robert Hirano

Its resources include approximately 8,500 plant taxa with about 4,000 species. Major collections are: Palms, 506 taxa; Heliconia, 106 taxa; Araceae, 354 taxa; Marantaceae, 199 taxa; Zingiberaceae, 113 taxa; Ficus, 99 taxa; Cordyline, 311 cultivars; native Hawaiian plants and Hawaiian Ethno-botanical Collection.
The first Vireya species and hybrids from the Royal Botanic Gardens, Kew, England, Rhododendron javanicum ssp. brookeanum var. gracile , cultivars, 'Pink Seeding', 'Red Prince', and 'Sir George Holford', were introduced to Lyon Arboretum from Longwood Gardens in 1967. Within a few years these plants began flowering: 'Pink Seedling' and 'Sir George Holford' flowered for the first time in July and August 1971 respectively; 'Red Prince' first flowered in 1973; and R. javanicum ssp. brookeanum var. gracile , received as R. brookeanum var. gracile , P.I. 257475 flowered for the first time in December of 1976. In 1972, a few more species were introduced to the Arboretum, including R. aurigeranum , R. cf. dielsianum , R. macgregoriae , and R. zoelleri . These plants were received as rooted cuttings and all flowered within two years. In a five year period, R. aurigeranum has been recorded in flower every month of the year; while R. macgregoriae has been observed in flower in every month with the exception of May and August. R. herzogii has flowered in every month except February, July and December. Since data collected was from a very small sample of plants, it appears that these species are capable of flowering in any given month here at the Arboretum. These plants have thrived and formed the nucleus of our Vireya Rhododendron Collection.

ARS Research Foundation logo

The early emphasis was placed in breeding and selecting ornamental types for Hawaii's climate. Many crosses and selfs were made and tested including many of Mr. Peter Schick's hybrid seeds and seedlings. We currently have over 35 hybrid taxa with over several hundred seedlings in various stages of evaluation. Many of these have flowered or are now coming into flowering. These hybrids are greatly contributing to the beauty of the islands with their bright colors.

R. aurigeranum x R. herzogii
R. aurigeranum x R. herzogii
Photo by Robert Hirano
(R. zoelleri x R. lochiae) x R. zoelleri
( R. zoelleri x R. lochiae ) x R. zoelleri
Photo by George Ring

Today, emphasis is on the development of a Vireya species collection in order that we may preserve the existing germ plasm of this extremely valuable group of plants for research and posterity. In November 1987, I was fortunate in collecting a Vireya species from the mountains near Banaue, Ifugao, Luzon, Philippines. The plant is now growing in our greenhouse and we are eagerly awaiting its first flowers. Only through plant collecting, exchanges, gifts, and purchases, will we attain our goal of establishing as complete a living outdoor collection of Vireya rhododendron at Lyon Arboretum. We now have a total of 29 species in the collection (see attached list). With help from the American Rhododendron Society and its members, this dream will become a reality and we will reach our goal of the 300 plus species listed by John Womersley in, A Census of the Species of Rhododendron, sect. Vireya . Many of the species growing today are clones, coming to the Arboretum as a vegetative cutting. It is our wish that someday, seedling populations of all the Vireya species will prosper on the grounds at Lyon Arboretum.

Vireya Rhododendron Species At Lyon Arboretum
26 February 1988
Accne# Species
72.203 R. aurigeranum
75.274 R. aurigeranum
82.701 R. aurigeranum
81.197 R. buxifolium var. robustum
82.699 R. christianae
72.207 R. cf. dielsianum
88.069 R. dielsianum
88.063 R. goodenoughii
73.232 R. herzogii
75.406 R. inconspicuum
75.407 R. inconspicuum
82.689 R. jasminiflorum
88.066 R. javanicum
67.142 R. javanicum ssp. brookeanum var. gracile
88.067 R. kawakamii
75.404 R. konori
82.631 R. konori
88.079 R. laetum
82.698 R. leptanthum
82.710 R. leptanthum
77.1038 R. leucogigas
88.070 R. lochiae
88.071 R. longiflorum
88.072 R. loranthiflorum
72.204 R. macgregoriae
88.073 R. pauciflorum
82.705 R. phaeochitum
88.074 R. retivenium
88.076 R. rhodoleucum
82.692 R. robinsonii
81.198 R. rugosum var. corifolium
82.700 R. scabridibracteum
88.077 R. solitarium
82.704 R. superbum
88.078 R. wrightianum var. wrightianum
72.205 R. zoelleri
72.206 R. zoelleri

Mr. Hirano has a long standing interest in growing Vireya rhododendrons in Hawaii. The ARS Research Foundation recently awarded an additional grant to the Lyon Arboretum for continuation of their work with Vireyas.