Leaf windows

While easily bored, the Phactor also can easily amuse himself as long as there is some nature to play with.  And you just never know what new thing you will see ifyou look carefully enough.  So while the various cousins amused themselves with the aquatic equivalent of motorcycles, the Phactor poked around in a nearby salt marsh just to see what you could see.  The seaside ox-eye (Borrichia frutescens) is a pretty common plant in such places in our part of the world.  If you know anything at all about plants it would not surprise you to find that the leaves were thick, succulent, and waxy, common features of plants in dry or salty environments that present similar problems for plants. But did you look closer?  The lower side of the leaf when held up to the light shows this attractive veiny pattern. The lighter green pattern is produced by clear areas, windows to the leaf's interior. Such windows are pretty common in other succulents, but came as an unexpected surprise here. The plant tends to hold its leaves more or less upright, thus presenting this windowed lower surface to the outside presumably so the morning or afternoon rays of sunlight can enter through the windows illuminating the green palisade layer from the bottom side. Most of the leaf mesophyll is almost devoid of chloroplasts.  This is an educated guess; anyone know for sure?