Rhododendrons
Throughout the modern history of UBC Botanical Garden, rhododendrons have been a high collection priority. The Garden began propagating rhododendrons in 1964 with the majority of the material for propagation derived from larger estates and gardens in the UK. Peter Wharton joined the staff of the garden in 1975 and was assigned to the continued development of the Asian Garden. Initially, the garden’s collections were derived in large part from the then sizeable storehouse of rhododendrons at the Botanical Garden Nursery, but it was not long before Wharton’s own Far Eastern seed collections and those of an ever-expanding network of botanical gardens and collectors began to be planted out. Peter spent more than 30 years developing the Asian Garden and he led or participated in nine field and seed collecting expeditions to China, South Korea and northern Vietnam.
Both in terms of numbers of taxa and overall beauty, rhododendrons have always been the backbone of the Garden. With the predominance of high, overhead shade, the larger leafed and taller growing rhododendrons are well represented. Some areas of the Asian Garden were initially heavily planted with the smaller lepidotes (scaly leaved rhododendrons), such as R. impeditum, R. luteiflorum and the ground hugging R. campylogynum and their relatives, but the more exuberant growth of surrounding plants tended to crowd them out and reduce the number of areas in which these smaller plants could be grown. Only in the more open E. H. Lohbrunner Alpine Garden do the smaller-leafed, sun-loving rhododendrons remain in their ascendency. There are particularly fine examples of the ravishingly purple R. canadense and the perfect, aromatic miniature R. lapponicum in the North American area, R. ferrugineum in the European section and a small number of other non-Asian species displayed in the Alpine Garden. However, as one would expect, Asian rhododendrons, primarily species and selections from Japan, the Himalayas and the mountains of western China (Asia is where the genus reaches its greatest diversity), are among the real jewels here.
British Columbia also has its share of Rhododendron species and the BC Rainforest Garden is where visitors can find a number of examples of R. macrophyllum and all three Labrador tea (formerly Ledum) species, R. palustre, R. neoglandulosum and R. groenlandicum. Cultivated in the Carolinian Forest Garden are wild-collected rhododendrons, including R. catawbiense, R. maximum, R. minus, and the deciduous R. canescens, R. arborescens, R. vaseyi, R. prinophyllum and R. calendulaceum. The majority of these species were collected as seed from the remarkably bio-diverse southern Appalachian Mountains.
Nitobe Memorial Garden is also home to a number of Rhododendron taxa, although these plants have never been part of the garden’s collections database. Like the Asian Garden, Nitobe was carved out of a natural second-growth stand, here composed primarily of tightly spaced Tsuga heterophylla (western hemlock) and Pseudotsuga menziesii (Douglas fir). This forest of straight stems and dark green foliage is the background to a restful landscape where shrubs, including a number of evergreen azaleas, have been clipped into homogeneous undulating masses, thus creating contemplative surrounding spaces on which to rest the eyes.
The Garden’s rhododendron collection is extensive. In total, the various areas of the Garden share approximately 450 Rhododendron taxa. All hardy subsections of subgenus Hymenanthes are represented and there is a wide selection of lepidotes (subgenus Rhododendron) and azaleas (various subgenera), although these collections are less complete, reflecting both the dearth of sunny, well-drained areas available and the somewhat traditional focus on larger rhododendrons for woodland planting. The Garden is not particularly well-endowed with respect to conventional hybrids. Notwithstanding a few exceptions, this reflects the prevailing attitude in botanical gardens about the value of hybrids relative to species and other naturally occurring taxa, and especially to collections of known wild provenance.
The range of Rhododendron taxa cultivated in the garden includes those derived from the more familiar and stalwart groups, such as subsections Fortunea, Saluenensia, Triflora and Pontica, as well as examples of many less well-known groups, such as subgenus Tsutsusi section Brachycalyx (the so-called three-leaf azaleas) and subgenus Hymenanthes section Pontica subsection Glischra (including the unusual R. glischrum subsp. rude, R. crinigerum and R. recurvoides).