John P. Evans, M.D., Oakland, Calif.
Taken in Strybing Arboretum,
Photo by Dr J. P. Evens
According to the classification of Dr. Sleumer*, R. zoelleri belongs in the Subgenus Rhododendron: Section Vireya: Subsection Euvireya: and Series Javanica. R. zoelleri is native to New Guinea and grows from sea-level to 1500, rarely 2000 meters. It is primarily a terrestrial plant, though it is reported to be weakly epiphytic in the forests at higher elevations. In habit it is open and erect and may reach 6 meters as a tree or shrub.
The truss of R. zoelleri is open, but is held well and consists of 4 to 8 flowers. The corolla is funnel shaped and lobed half way. It is quite striking in color, from yellow to orange or salmon in the tube, with orange red to red suffused into the lobes. In the color illustration the corolla measures 8.2 cm. across the lobes and the tube 6.1 cm in length. The R. H. S. Color Chart shows that the exterior of the tube is Yellow Orange 15 AB, and its throat is Yellow Orange 17 AB, while its lobes are Orange Red 33 B.
The photo shown was taken of a plant in flower in the Strybing Arboretum grown by Pete Sullivan from seed sent to Strybing by Tom Lelliott of Australia in 1967. A sister seedling is to be named "Golden Gate" in honor of the 100th anniversary of Golden Gate Park this year.
Those of us in the California Chapter who grow this species find it a very pleasing outdoor garden plant blooming from seed in 3 to 4 years. It withstands our mild winters well. Our interest in the Vireya Section is intense because its members offer colors not found in the other well known Sections. Our goal of course is two fold, intra-specific crosses, and attempts to hybridize with our Maddenii Series. The latter has been tried on a small scale but to date no break through has been reported here or in Australia.
*H. Sleumer: An Account of Rhododendrons in Malesia: P. Noordhoff Ltd. Groninger, The Netherlands.