My current favorite is dwarf Sagittaria, and a photo is at:
http://www.cco.caltech.edu/~aquaria/Krib/Plants/Plants/Sagittaria.jpg
Mine grow quickly, and have covered every well-lit area (and some
not-so-well-lit). They are about 2-3 inches high. I must have 100+
plants by now. I had a small patch of E. tenellus, but the Sags
overrran and conquered them.
Thank you, Cynthia.
Regards,
Mark