Brown \ˈbrau̇n\ , Robert (1773–1858), British botanist. Brown was one of the leading botanists of his day. In 1801 he accompanied a surveying expedition to and around Australia, acting as the company's naturalist. In 1805 he returned to Great Britain with about 3,900 species of plants, and in 1810 he published a great work on the flora of Australia. In the field of botany he is also known for his substantial contributions to plant morphology, embryology, and geography, for improving plant classification and making a fundamental distinction between gymnosperms and angiosperms, for establishing and defining new families and genera, and for describing and naming the nucleus of a plant cell. He published his observations on Brownian motion in 1831.