The flowers are 3.5–5 cm diameter, with five lobes on the corolla; color varies from white to pink, often with a yellow blotch.

For this reason, it is a part of the unique plant community found in the serpentine barrens of the Siskiyou Mountains, along with Darlingtonia californica and Cypripedium californicum.

Rhododendron occidentale was described by explorers in western North America in the nineteenth century.

During the twentieth century it has been the subject of ongoing plant exploration as at least three generations of rhododendron enthusiasts have sought out unusual forms for use in the garden and to record for science.

Many of those forms are now conserved in the Smith-Mossman Western Azalea Garden at Lake Wilderness Arboretum in Maple Valley, Washington state, USA.