Infinite Lettuce?

So, about a bajillion people on pinterest have posted links to articles like this and this, in which the writers say that you can take the stump left from a head of romaine lettuce and re-root it and re-grow more lettuce from it.  Which suggests that at least some types of lettuce are pretty sturdy.

Also I see articles like this one about "cut-and-come-again" harvesting of loose-leafed lettuce, in which  you just chop off the top portion of the lettuce head and leave it and it'll grow back from the base.  This seems rather consistent with the ability to grow back again from the stump, so I'm starting to see a pattern here.

And it sure seems like it would let you get more lettuce from less space, if this approach works - I strongly suspect that a lettuce stump with an established root system would grow back to harvest-able size faster than a new head would grow from seed, right?

So just tried it.  Went outside, whacked off the top half of the three lettuce heads that are currently big enough to harvest, and made a nice salad (yum!).

We'll see what happens - whether it grows back, and how long it takes.  I'll be sure to report back here!

Close-up of chopped off lettuce.  Tried to cut it high enough that the smallest of the developing new leaves would be un-affected.  I left a couple of the outer leaves as well, mostly because they seemed a little beat-up and weren't appealing for salad. 

Whacking down a few of the plants gives others space to spread out (there were five plants in this clump and I cut back three of them). In a perfect world I can imagine that now the remaining two will have a growth spurt because of their new space to spread out, and then as the three re-growing plants get bigger, I can cut down the two big ones to make space, and continue to alternate so as to maximize the lettuce harvested from this little space.