Mr. Dionigi has described what must be a Liverwort. Riccia is a purely aquatic Liverwort, but apparently there is at least one more! As a general reference on plants, both terrestrial and aquatic, try The Liberty Hyde Bailey Hortorum's Hortus Third. A surprising number of our plants are there! Hope this helps. Cheers! Jean Olson JOlson8590 at AOL_com Out in the Boonies, near Cambridge, Iowa