Thistle, Star;  Centaurea solstitialis

Late bloomer.  Yellow spiny flowers, highly invasive alien weed!  Can kill animals, eradication difficult.

Notes:  Aster (Sunflower) family.  From Asia. Best controlled by pulling up plant before they go to seed, as one plant can eventually have 80,000 seeds.

Click on genus name below to go to USDA for this genus.

Kingdom Plantae -- Plants
    Subkingdom Tracheobionta -- Vascular plants
        Superdivision Spermatophyta -- Seed plants
            Division Magnoliophyta -- Flowering plants
                Class Magnoliopsida -- Dicotyledons
                    Subclass Asteridae
                        Order Asterales
                            Family Asteraceae -- Aster family
                                Genus Centaurea L. -- knapweed
                                    Species Centaurea solstitialis L. -- yellow star-thistle

Thistle, Star;  Centaurea solstitialis
(ŠJ.S. Peterson. USDA NRCS NPDC)