Way back when I was in college - the late 60s - I knew of a spring about 20 miles away where Riccia grew. Yesterday, returning from a trip to another town, I swung by there. Much had changed - the spring itself is now fenced in with a springhouse erected and a sign that tampering with the property is a federal offense - apparently it is a water supply for a local community. But the runoff is still accessible. It was cold and I was dog tired but I took a quick look and saw lots of interesting vegetation. For sure I saw hornwort and Sagittaria platyphylla; I am pretty sure I saw Ludwigia and Samolus. There was quite a bit I just could not get close to without getting wet and it was just too cold to go wading! Wait until next summer! But I saw no Riccia... I wished that I'd brought my camera along but I didn't. This is central Alabama, BTW.