If asked which plant would be the first to suffer from drought, between Coleus & zigzag (Euphorbia / Pedilanthus tithymaloides,) I would have *known* it was of course, the Coleus.
Clearly losing all of its' foliage isn't as bothersome to the zigzag, but I do find it fascinating that the condition became so dry that the zigzag couldn't maintain any foliage and didn't kill the Coleus. All of the zigzag foliage is new since taking this pot outside where I could water it copiously, often.
Out of laziness and having at least a dozen other pots with these same plants, I was monitoring the Coleus leaves for loss of turgidity to decide when to water. That wasn't enough moisture to keep foliage on the zigzag. Other zigzag individuals in pots given less neglectful watering stay foliated all winter.