haven't found "piel flor" but "flor de piel lanar" (skiver) and "flor de piel cabria" (goat skiver), check it out ref. below. hope it helps anyway... :)

<<Full-grain leather
The top surface of a leather, corresponding to the external part of the skin, that has not had the grain removed mechanically.
The advantages of a full-grain leather glove: good manual dexterity, comfort, and precise touch.>>

http://www.deltaplus.fr/GB/index.html

<<Todo flor
Es un tipo de piel que se encuentra por encima de la parte externa de la dermis y que no ha experimentado ningún tipo de corrección.
Ventajas del guante en piel todo flor : proporciona habilidad en los movimientos, confort y gran sensación táctil.>>

http://www.deltaplus.fr/ESP/matieres/cuir.html

Have a look at the reference URL's, and you´ll find a lot of information on this topic, both in English and Spanish.

Hope it helps.

'Piel flor' must be a term from shoemakers slang, but it looks like a young, tender material, like calfskin.
Luck!