Hydrangia Pâté (née Bouvier) was the daughter of Edmund Bouvier and Clématis de Fleur. She was the wife of Cecil Pâté, and had a son Seymour Bouvier. Her sisters were Lolita Bouvier, Wysteria Bouvier and Juniper Bouvier.
In many cultures it is traditional for the wife to take her husband's surname when she marries, and any children born would also have the husband's surname. However, in The Simpsons Uncensored Family Album, Seymour is shown as having the surname Bouvier. This does not appear to be a middle name and it is unknown what circumstances led to Seymour having a different last name than his father.