Dodonaea, commonly known as hop-bushes, is a genus of about 70 species of flowering plants in the soapberry family, Sapindaceae. The genus has a cosmopolitan distribution in tropical, subtropical and warm temperate regions of Africa, the Americas, southern Asia and Australasia, but 59 species are endemic to Australia.

Plants in the genus Dodonaea are shrubs or small trees and often have sticky foliage, with simple or pinnate leaves arranged alternately along the stems. The flowers are male, female or bisexual and are borne in leaf axils or on the ends of branchlets and lack petals. The fruit is an angled or winged capsule.

Plants in the genus Dodonaea are shrubs or small trees that typically grow to a height of 0.1–4 m (3.9 in – 13 ft 1.5 in) and are dioecious, monoecious or polygamous and often have sticky foliage. The leaves are arranged alternately along the stems and are simple or pinnate. The flowers have three to seven sepals but that fall of as the flowers mature, but no petals. There are six to sixteen stamens (except in female flowers), the filaments shorter than the anthers, the style is threadlike and the ovary in female flowers has two to six carpels. The fruit is a two to six angled or winged capsule.

The genus Dodonaea was first formally described in 1754 by Philip Miller in The Gardeners Dictionary and the first species he described was Dodonaea viscosa. The genus name (Dodonaea) honours Dodonaeus, (the latinised form of Dodoens), a Flemish physician and botanist.

Dodonaea is one of the largest genera in the Sapindaceae, and includes 70 species widely distributed in continental Australia. The only other species of the Dodonaea widely spread beyond mainland Australia, Dodonaea viscosa, is believed to be one of the world's most greatly disseminated transoceanic plants.

The first attempts to distinguish infrageneric categories within genus Dodonaea were based on leaf morphology, specifically, two sections - Eu-Dodonaea (simple leaves) and Remberta (pinnate leaves) were differentiated. Later this sectional classification was expanded by Bentham, who included 39 species in five series - four simple-leaved series further divided on capsule-appendage morphology (series Cyclopterae, Platypterae, Cornutae and Apterae) and one pinnate-leaved species (series Pinnatae).

Later the genus was reviewed extensively two times. Radlkofer identified Dodonaea as a part of the tribe Dodonaeeae, within Dyssapindaceae, together with Loxodiscus, Diplopeltis and Distichostemon. Dodonaea and Distichostemon share similar morphological characteristics which include plants having regular flowers without petals and an intrastaminal disc. Therefore, these two genera are considered to be closely related.

54 Dodonaea species identified by Radlkofer were divided into three series (Cyclopterae, Platypterae and Aphanopterae) and six subseries.