There is a lot of hearsay and copy paste regarding the attribution of the name:
- Journal des Roses of January 1910 says: dedicated to a lady of Grenoble, a lover of flowers
- Biltmore roses catalogue of 1913 : "named in honor of a distinguished and enthusiastic Rose-lover"
- House & Garden of 1929: "a fashionable couturière of London" [20th century books say a fashionable dressmaker of Grenoble who had salons in Paris and London!]
- The Gardeners Chronicle of May 29, 1937: "wife of a friend and customer of his who was a leading magistrate in Grenoble....M. Testout was an enthusiastic amateur gardener and had considerable success locally, principally in raising Gladioli"
- Les Amis des Roses of December 1939: wife of a magistrate of Grenoble

Now for some fact checking:
- There is no evidence of a couturière/dressmaker named Testout or Testoud in Grenoble, Paris, or London. If she was so successful, we should have found some trace of her on the web. This seems a made up story.

- The name Testout or Testoud is indeed common in the Grenoble area
- An Adolphe Testout bred a chrysanthemum 'Vaucanson' in 1893. No info on gladioli.
- A magistrat in France is a member of a court. There was indeed a A. Testout who was at the Court of Appelation in Grenoble in 1882. He is, however, mentioned as an amateur entomologist. Is this the same as Charles Adolphe Edmond Testout (January 17, 1845 - May 13, 1912 Grenoble)?
- The Zoologisches Adresssbuch of 1895 lists (p. 274) a Ch. Testout at 112 Cours Berriat, Grenoble, with collection of insects and butterflies. He is a Greffier (clerk) at the Court of Appelations. This address is a multi-story apartment building in the centre of the town. No garden in sight.
- Earlier, in 1855 a M. Testout is mentioned as propriétaire (landowner) in "La Frise, près de Polygone, 10 minutes de Grenoble". This La Frise is not far from the Cours Berriat above.
- A Mme Testout was a science teacher at the gymnasium for girls in Grenoble until 1901. Was she named Caroline?