@ctrl-alt-nwo, That's very interesting blog post about Spiraea. Beautiful bunch flowers indeed. Among the easiest flowering shrubs to grow, spireas are often used in foundation plantings, as hedges, and in perennial gardens. Most spireas bloom in late spring to midsummer. Flower colors include pink, red, yellow, and white, depending on the variety. Some types have colorful fall foliage. Size depends on the species and variety, and can range from 2 to 10 feet tall and wide. Low-growing bumald spirea (S. bumalda) and medium-sized Japanese spirea (S. japonica) can be used throughout the landscape. Vanhoutte spirea (S. vanhouttei), the classic bridal wreath spirea, grows up to 10 feet tall and 20 feet wide, so give it plenty of elbow room. Masses of small, white flower clusters cover the plant in the spring.
Spireas are small to medium sized deciduous shrubs that produce cascades of flowers in spring and summer.
Good comment with some extra info.