Today I was out in the pasture by 8:30.... before breakfast... before it got too hot. I was equipped with clippers (which I lost in the pasture at one point), a big black pot and a sprayer of Round-Up. I was snipping flower heads off the thistles and spraying the plants. We are slowly making headway against the thistle problem in our yard and pasture.
I came across a thistle-like plant, but the flower buds (in picture above) were very different. They had a spiny covering and four or five pointed spines. The buds, all by themselves, looked sinister. They looked like they had gaping jaws.
When I cut the tops of the stem, removing the flower buds, the plant 'bled' tempera paint yellow! The yellow in the picture below is not a flower, it's the sap of the plant! It welled up, just like blood would behave if you were cut. It even ran down the stems. "Little Shop of Horrors" immediately came to mind!
I love the Internet. A search for "thistle plant yellow sap" yielded my answer. I discovered that this is Mexican Prickly Poppy (Argemone mexicans). It is also known as goatweed, Mexican thistle and yellow thistle. The flowers are quite pretty. But, I don't think Ill be cutting a bouquet of them anytime soon!