Former Merchant flag of Portugal.
Own work
According to La connoissance des pavillons (1737):


Pavillon de Marchand Portugais. Il est de sept bandes mêlées, qui font, à commencer par la plus haute, l’une verte, &amp; l’autre blanche.
(trans.: Merchant Flag of Portugal. It has seven mixed stripes, which are, starting with the highest, one green, and the other white.)
Jsobral