The bottlebrushes are twenty-five or thirty species of shrubs and small trees native to Australia and New Caledonia. The rigid bottlebrush (Callistemon rigidus) was discovered by Robert Brown during the mapping and exploration of "New Holland" (Australia) by the HMS Investigator (1801-1803). Brown established the genus Callistemon "beautiful stamens" in 1814; it was published in A Voyage to Terra Australis, the account by Matthew Flinders, the captain of the voyage. English gardeners began growing Callistemon rigidus around 1815 before the species was even formally described and named in 1819.

The flowers of the bottlebrush are tightly arranged around the ends of the branches. The floral parts are greatly reduced except for the numerous long stamens. The flowers attract both insects and birds. After pollination, the three-chambered ovary hardens into a capsule. Each capsule is filled with a myriad of tiny seeds. The capsules, looking like rows of little wooden cups, remain on the branch; in some species for years.

Once the seeds begin developing, the branch resumes growing and putting on new leaves. The end of the new growth will carry the next year's flowers. The branches appear somewhat odd—lengths with leaves alternating with lengths covered in tiny wooden capsules. The seeds need at least a year to develop; in some species, the seeds are not shed until the branch or even the entire tree dies.