Sida

Called ironweed by some because of its tough stem, Sida rhombifolia is an introduced weed that is also difficult to pull out after it has grown into a small shrub. It's easily killed by cutting at ground level and putting a drop of glyphosate weedkiller on the cut surface.

It comes up prolifically in exposed areas and is easier to get rid of by hand weeding at the early stage shown in the photo.