Genus - Buddleia
Sometimes spelled as Buddleja, it is more commonly known as Butterfly Bush. The genus contains over 90 species. The genus is named after the reverend Adam Buddle, an English botanist from the late 1600's. As it's name suggests, it is irresistible to butterflies. It also popular with bees and moths.
Culture - Buddleia should be planted in full sun. They do not like to be in wet spots and generally are drought tolerant. Many cultivars can die back all the way to the ground in severe winters only to snap back in the June. It is important to note that this genus is slow to break dormancy in the spring. If your plant has not yet grown foliage, be patient, it is probably not dead but just dormant.