spotted/prostrate spurge (Euphorbia maculata)
native, weed
picture taken in june
spotted spurge is also called prostrate spurge, creeping spurge, and spotted sandmat! it is a parking lot weed, growing happily between the cracks in pavement and sidewalks; it likes full sun and sandy nutrient-poor soil. it grows in flat circular mats - and, interestingly, its long reaching stems don't put down roots. unusual for a creeping plant!
spotted spurge has distinctive maroon spots on the leaves, which help distinguish it from similar parking-lot weeds.
it seems there's a bit of debate over whether spotted spurge and prostrate spurge are different species! there is a spurge which grows and looks like this one but doesn't have spots; one of my books (wild urban plants of the northeast) says that this is spotted spurge minus spots, but another (weeds of the northeast) argues that the spotless kind is different. the latter source identifies two differences: prostrate spurge has no spots, and does root from its stems.
spotted spurge has milky white sap which irritates human skin. it's also toxic to livestock and can choke out chunks of grass lawns if you let it, so it has a lot of haters! i'm having trouble finding information on how toxic it is to animals, so probably not very; i think it just makes them sick but doesn't necessarily kill them.