The burgundy spurge I got only this year and am not happy with its placement. When it cools off, I may move it. But the chartreuse one is in a perfect place. I have read in my research that others find these spurges too invasive. Thus far in my garden, I have been able to weed unwanted interlopers. This way I enjoy the spurge's spring display of not-quite-flower flowers.
The crown of thorns is a relative of the spurge, also being a euphorbia. Here it is in medium size.
The smaller size is pictured below.
All euphorbias are succulents, so require less water than most plants, thus surviving the heat and drought. The poinsetta is also part of this larger species of euphorbia. What a varied group of plants!!