any of a genus (Callistemon) of shrubs or trees of the myrtle family, having flowers with conspicuous tufts of red or yellow stamens and cultivated in warm climates
See bottlebrush in American Heritage Dictionary 4
noun
Any of various Australian shrubs or trees of the genera Callistemon and Melaleuca, having densely flowered, cylindrical spikes with numerous, long, protruding stamens that suggest a brush used to clean bottles.