Need help with plant ID

[dr_girlfriend]

I picked this up at an auction. The only discription was "horse hair". Someone said it looked like green foxtail, but I'm not sure.

 

[malkore]

I think it looks like green foxtail too, this one "cutleaf watermilfoil"
Myriophyllum pinnatum
http://www.plantgeek.net/plantguide_viewer.php?id=170

 

[dr_girlfriend]

Cool, thanks. I looked at a few more sites with pics and I think youre right. How do you plant this in the substrate? It has no roots. Should I place some rocks on it till it does?

 

[malkore]

You should be able to tell which end is the bottom (the leaves/fronds should be angled up slightly). Just plant the base in the substrate. It'll root down eventually.