Philadelphus lewisii (Mockorange)
The state flower of Idaho, it gets its common name from the delicious orangey scent that makes it attractive to bees and humans alike.
Flowering for several weeks starting in late May or early June, the tall, arching branches are covered with a multitude of snow-white blossoms of usually four petals, pale yellow in the center. After the petals fall, the sepals remain in a way that looks like a second, different type of flower, providing some longer seasonal interest.
The oval leaves start out in the spring as a soft green and turn yellow in the fall.