Dicot.  Flowers are very small and crowded into compact heads resembling a single flower.  Two kinds of flowers present:  showy petal-like ray-flowers on the outside of the head, as in sunflowers and daisies; tiny tubular flowers forming the disklike center of the head.  In some members only ray flowers or disk flowers are present.  Flower heads are surrounded by modified leaf-like structures called bracts or phyllaries, called the involucre, which superficially resembles the calyx of other flower types.  Ovary forms a one-seeded fruit called an achene.

Arnica parryi (Parry's arnica)

Cirsium arvense  (Canada Thistle)

Chrysothamnus viscidiflorus (Green Rabbitbrush)