The leaves of Robinia are pinnate with 7–21 oval leaflets. The flowers are white or pink, in usually pendulous racemes. Many species have thorny shoots, and several have sticky hairs on the shoots. The genus is named after the royal French gardeners Jean Robin and his son Vespasien Robin, who introduced the plant to Europe in 1601. The number of species is disputed between different authorities, with as few as four recognised by some authors, while others recognise up to ten species. There are also several natural hybrids.