Charlie, I moved your post and bob's response post out of the other thread and started a new thread. The topic is new so a new thread is best.
As bob said, the "stem" is what we call a flower stalk or, to give it is proper name, an inflorescence. When the plant is grown submersed, flowers rarely appear on these, but adventitious plants, sometimes called daughter plants or plantlets, will grow from the nodes. You can leave all this, or remove some or all of the adventitious plants when they are of sufficient size which means leaves about 2-3 inches and some white roots. You will usually have two adventitious plants from each node; they will look like one but when you remove them you will see they are actually two distinct plants.
Runners are not formed by plants in Echinodorus. The commonly-called Pygmy chain sword
and Chain Sword
plants do form runners, never inflorescences if grown submersed, along the substrate from which adventitious plants (never flowers) will appear at regular intervals. These species used to be in
Echinodorus, but are now in Helanthium. Read more in the profiles (click shaded names).
I mentioned submersed growth; these plants are all bog or marsh plants, spending half the year submersed and half emersed. Read more on this in the profiles, example Echinodorus bleherae