This is Fendlera rupicola, also known as Cliff fendlerbush, and False mockorange. From late Spring to early fall Fendlera rupicola has white blossoms. Growing up to 4 feet tall Cliff fendlerbush likes to live in full sun to partial shade. The Navajo indians used False mockorange for killing head lice, and for making shafts which they use to make arrows, forks, and knitting needles. False mockorange is also used in ceremonies. USDA Hardiness Zones 5 to 8.