This fast-growing, deciduous tree was introduced into the U.S. in 1745 as an ornamental. It is relatively short-lived, although hardy to -30º and in California, grows at least 25% to 40% taller than its generally accepted height of 25' - 30'. Here, there are some quite large specimens and in bloom, at some distance, they look a bit like a huge pink toilet brush. The species was named for the Italian scholar Albizi, who introduced the plant to Europe in the early 18th century.
The genus Albizia is of the subfamily Mimosoideae of the legume family and grows in most tropical and subtropical climates. The bark or cortex is used to heal bruises and as a vermicide. I was surprised to notice that the flowers have a distinct sweet smell, usually only close up - otherwise, the scent is very faint and not localized.
The tree's Persian name is Shabkhosb, "the Night Sleeper" and in Japan Nemunoki, or "Sleeping Tree", from the leaves' habit of slowly folding downward at night as if it was sleeping. In Haiku, the flower's name represents summer.
The leaf movement mimics a true Mimosa, Mimosa pudica or "Sensitive Plant", native to Mexico and Central America. In Hawaii and a number of other areas it has become an invasive weed. It is one of the few plants, along with the Venus Flytrap and the Telegraph Plant, that are capable of rapid movement.
Image courtesy of USGS