Stinging Nettle, Urtica dioica, hosts the Satyr Comma, Milbert's Tortoiseshell, and others. This plant is common in our mountains and foothills, especially near streams and other moist areas.
The nettle plant has culinary and medicinal uses. But don't touch the stems - I made this mistake, barely touching one; the pain in my finger lasted about twelve hours. These "hairs" are like little hypodermic needles that break off, delivering a dose of histamine, serotonin, and acetylcholine.