Y'all that are saying these things are easy to remove must never have removed them before.
As for type of plant, they are desert plant, therefore they have a root system that doesn't end. They are not that easy to get rid of permanently.
Also, if you don't think they are useful and for sale, you are not much of a landscaper. I planted some a few years back, by my house. In a rock garden. Planted some others about 10-15 years ago, around a house where they wanted a southwestern look.
"Science is the belief in the ignorance of the experts" – Richard Feynman
Guns don't kill people, abortion clinics do.