I posted last February about this plant and didn't see the two subsequent posts for further information until this morning. Sorry 'bout that!
The botanical name is Malvaviscus arboreus 'mexicanus' or 'penduliflorus'. It doesn't look much like 'drummondii' at all. The blooms are much, much larger and are pendulus (as the name suggests). I'm not sure if the plant is available in the trade; I got mine by rescuing some plants prior to their destruction by bulldozers. They root quite easily, rooting wherever a branch remains in contact with the ground. I've looked through my digital images, as well as slides, and can't find a picture. If you're that interested, I can try to get my husband to take a picture.
A friend I gave a start of this plant last spring is absolutely wild about it. Ours are in full bloom (here in Zone 9b). Mine can reach to about 10' in height. In cold winters, they have some die back but have been completely root hardy for about 10 to 12 years. The shrub itself is not the most beautiful one in the world. It's long branches droop and its foliage is large and somewhat similar to a Confederate Rose (to which it's related). Still, I really love it, having three large examples in my garden. It's definitely worth pursuing - particularly in zones 9b and warmer where it remains in bloom during the winter. In fact, if unpruned I think it'd be in bloom most of the year (at least the ones I didn't cut back were).
Leslie
Mexican or Giant Turk's Cap
I've seen shrubs that have been nicely pruned along the way, so they are full and not straggly. One house nearby has them as a low hedge. This was the first plant I fell in love with upon moving to Texas, because the red is such a gorgeous red and the blossoms are so interesting the way they droop. I have seen them for sale. A nursery near me carries them all the time, both the red and the pink versions. I tried one but it never took hold in our salty soil and finally died after the salty flooding we got from Ike. It is not as salt tolerant as M. drummondii, it seems to me.