The Plains Coreopsis (tinctoria) that I have growing here in SC looks more or less identical to yours, with the same blooms and thin/fine foliage. Also, there are a lot of photos online that show Plains Coreopsis (same color bloom) with foliage like the photos you posted...
check out
http://animpartationofcolor.bl... -- it shows an entire plant layed over on it's side and the foliage is clearly the same as in the picture you posted.
and also this online seed catalogue --
http://www.lifeseedcompany.com...
Not sure why it looks so different in the DB pics... very interesting...
