France - Le Havre (Seine Maritime)
French botanist, brother of Ferdinand Cayeux; was director of Gardens and walks of Havre, director of the botanical garden of Lisbon.(see: Richard Cayeux, Histoire de la Maison Cayeux, Hommes et Plantes n° 25, 1998 or Iris et Bulbeuses, n°134, 1999, pp. 10-14).
Other members of the Cayeux family: René (nephew), Jean (grandnephew), Richard (great-grandnephew).