It looks like american pondweed to me.

Read this and tell me what you think: http://www.texasinvasives.org/plant_database/detail.php?symbol=SAMI7


www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).