Grindelia squarrosa (Gumweed)

This plant can grow to three feet with multiple stems and become a real nuisance. It has basal leaves with serrate, clasping leaves and is a perennial. To understand why it is called "Gumweed," just touch a bud.

 

 

This photo shows the attachment of the leaf to the stem. There is no leaf stem, hence the leaf is sessile.