The life cycle of a star thistle is interesting to me. They start life as soft, sort of pale plants. When they mature they are all points and angles with a lovely but dangerous looking blossom. It's just awful to have to walk through a field of them on a hot summer day. When their season ends and they all die, they become grey and brittle. I've said before that they remind me of bones. Centaurea solstitialis is the name of the species that grows around here. They're an invasive species originally from the Mediterranean region. Acording to Wikipedia they currently dominate over 18 million acres in the United States alone, and it's toxic to horses.