Naturalist Diann Henderson will speak at the Camden Public Library on Thursday, March 23, at 7 p.m. about common lichens that can be found on the Mt. Battie Road in Camden Hills State Park. There will be a PowerPoint presentation, as well as hands-on samples of lichens to learn from — bring a hand lens if you have one. Henderson will also lead a Mt. Battie Road lichen field trip on Friday, March 24, from 9 to 11 a.m., rain or shine. Those interested should meet at the Camden Hills State Park parking lot at 8:45 a.m. Wear appropriate clothing to walk in the woods, a raincoat and boots if needed. A notebook, pen and hand lens will be useful.