Rh. sinogrande was first discovered in China by George Forrest in 1912 and it first flowered at Heligan in Cornwall in l919. It can reach 30 feet in height and the leaves can be 15 inches long
Rh kesangiae is a recent introduction from
Bhutan. There is a white form as well as the pink.
Rh macabeanum is a native of Assam and was discovered in 1882 by Sir George Watt. It can make a tree of 40 foot in the wild and its leaves are up to a foot long. The flowers vary from a pale sulphur yellow to a deep yellow.
Rh. montroseanum (also known as mollyanum) seed was collected by Frank Kingdom Ward in Tibet and was raised at Brodick. It is a large plant with long narrow leaves and striking pink flowes.
The fifth Grandia Rhododendron to be found in the Garden is Rh siderum which has yet to flower.