Accessions: 000385-0039-1964 and 000184-0024-1965 Location: Asian Garden, south of Lower Asian Way at Farrer Date: July 11, 2012 The dark purple markings on the petioles attracted us to these plants. There's a grove of them, with the tags that we could find being on two individuals that were not the ones we photographed.
R. orbiculare told from related species by the leaves being circular to ovate-circular, 1.2-1.5x as long as broad. R. orbiculare subsp. orbiculare distinguished by its leaves being 7-9.5 cm long, about 1.2x as long as broad. Ref: Cullen, Hardy Rhododendron Species - A Guide to Identification, 2005, Royal Botanic Garden Edinburgh/Timber Press, Portland I'm wondering if the leaves in a couple of the pictures here are too elongate to fit the bill. I've seen apparently hybrid seedlings raised from open-pollinated seed of this species betray themselves by producing insufficiently rounded leaves.
