Yellow Star Thistle

Centaurea solstitialis

It was nearly dark before I got around to taking a photo this evening. This plant is an invasive alien that has taken over in some areas of California. If you see a green hillside around here this time of year, it's a bad sign. All the grasses have turned yellow or brown, but the stems and leaves of this invasive plant are green. When it grows alongside hiking trails, the spikes on the flower heads are painfully sharp on your shins. It's poisonous to horses, and the cattle don't like to eat it. It crowds out grasses and native plants and flowers. I'm told the only positive about it is that it's good for the bee industry.