Can someone help pls?
Thanks a lot!
I am not sure of the ID of your plant. Perhaps a closer view of the flower and leaves would help. But I did find some neat links to wildflowers of Portugal that may be of use for an ID.
I agree with Altagardener, a species of Amaranthus....this link has a list at the bottom of the page for species found in Portugal.
That was my other thought, and from the look of the flower, I think you're right, growin.