Asterella tenella (L.) P. Beauv.
[identified by study of a paradermal section to view the dorsal epidermal cell walls and the pattern of the cells surrounding the air chamber openings]
Photo by Li Zhang
USA. Illinois. Johnson Co. Ferne Clyffe State Park, Black Jack Oak Trail. On sandy soil on exposed sandstone rock glade, 180 m, May 31, 2009. Zhang 6331 (voucher in SZG)