Count Alexandre Henri Gabriel de Cassini (May 9, 1781 – April 16, 1832) was a French botanist and naturalist, who specialised in the sunflower family (Asteraceae) (then known as family Compositae).
He was the youngest of five children of Jacques Dominique, Comte de Cassini, who had succeeded his father as the director of the Paris Observatory, famous for completing the map of France. He was also the great-great-grandson of famous Italian-French astronomer, Giovanni Domenico Cassini, discoverer of Jupiter's Great Red Spot and the Cassini division in Saturn's rings.
The genus Cassinia was named in his honour by the botanist Robert Brown.
He named many flowering plants and new genera in the sunflower family (Asteraceae), many of them from North America. He published 65 papers and 11 reviews in the [Nouveau] Bulletin des Sciences par la Société Philomatique de Paris between 1812 and 1821.
In 1825, Cassini placed the North American taxa of Prenanthes in the new genus Nabalus, now considered a subgenus of Prenanthes (family Asteraceae, tribe Lactuceae).
In 1828 he named Dugaldia hoopesii for the Scottish naturalist Dugald Stewart (1753-1828).
Some genera (originally) named by him :