I was redoing my 10 gallon tank just now and I went into my 55 gallon tank to pull up some plants to put in there. From two inch deep Special Kitty brand kitty litter I pulled up following root system:
One of the two little baby plants was almost completely underground when I went to pull the plant up, to help give you a sense of where the line of ground was. The plant went two inches down and then spread out from its central root stalk like someone opening an umbrella. It really impressed me. I started tugging expecting only to have slight resistance in pulling the plant out and ended up tugging with quite a lot of force and eventually ripping half the roots instead of getting them all out. Meanwhile the fancy pants plant on the other side of the tank won't grow enough roots to hold itself down. This myriophyllum pinnatum is now one of my favorite plants
Edited by EricaWieser, 11 June 2012 - 08:23 PM.