I can't see detail well, but was thinking it looked like a broom, like Cytisus.

Could be Baccharis sarothroides.

Thank you Cytisus: I thought you were joking, but it is a real Desert broom.
Nonmember: Thank you for telling me the Baccharis sarothroides. Now I have known its real name. I checked with Google search, it's also call Desert broom, it is a butterfly attracting shrub. Three of my neighbors has this weed. Instead of seeing butterfly (the butterfly here is as rare as the desert rain), there are millions of annoyed tiny (about 1/8 inch) beetle crawling around these shrubs.