I started a thread in the plant ID forum titled Maltese Star Thistle (Centaurea melitensis) because there were your photos of a blue flower and also from Joy. The rest were from Kelli of the yellow invasive one. I can only guess how yours and joys got in there..... at the time there was no separate entry for C. americana because that name was listed as a synonym for C. melitensis on whatever source they were using at the time and that is still unresolved across all the sources used. Janet did find an old reference with a color plate 51 labeled Plectocephalus americanus which may also be the name or just a synonym of yours and Joy's flower. Evan has now made an entry for C. americana, your flower, even though the name is not resolved. It is a temporary fix but better than having photos of two species in one entry. I hope this was a little less confusing. I think I read it all through with the links a dozen times or so myself. I hope I have it right now!
