Just a few thoughts on how we mature as field scientists (pardon my biases). Partially due to my being an avid photographer, over the years of wandering about the great outdoors, I have become more observant of things besides rocks and other Geology-related things. Having some working knowledge about plants, fungi, animals, etc. can help keep students attentive during field trips. (After all, we ARE Earth Scientists.)
False Purple Thistle (Eryngium leavenworthii), I call it "a flower with an attitude". I first encountered this plant on Caverns of Sonora Road, south of I-10, west of Sonora, Texas in 2016.
It looks like a thistle, but it isn't. It is native to KS, AR, OK, MO, TX, and WI and it seems to prefer limestone-based soils (as seen by this specimen on the Edwards Plateau, west of Sonora, TX). It is usually found in rocky prairies and open woods. The nectar is good for pollinators and the seeds serve as food for birds.
False Purple Thistle - Lady Bird Johnson Wildflower Center
False Purple Thistle - Weedin, Waterin, Watchin Blog