Field Thistle,  Cirsium discolor
Asteraceae or Sunflower Family

Tall erect, viciously prickly, but very pretty plant.  The leaves and flower heads, but not the stems, are covered with spines.  Leaves deeply and irregularly cut and lobed, spiny at lobe tips, and white wooly underneath.  Flower heads typical of a thistle, about 1-1/2 to 2 inches tall, with a multitude of long-petaled purple flowers.  Blooms in the summer

A native plant of fields and roadsides.  Occasional along the bike path, along Wildwood Drive and around the butterfly meadows.

The alien bull thistle (Cirsium vulgare) has larger flowers, no white wool on the leaves, and spines all down the stems as well as on leaves and flowers.