White flowers on tall shrubs, growing near road in forest.
Robust plants on south side, near water.
Hundreds of Rhododendron albiflorum, or White Rhododendron, grow along the Grand Ridge trail at 5000'. I had only seen three individual plants previously, so it was amazing to find so many! Most were fairly close to the Deer Park trailhead.
This is Rhododendron albiflorum, or White-flowered Rhododendron, which I've only seen twice before. It was growing on the Klahane Ridge trail and conveniently labelled by park rangers.