Plants with fleshy stems that store water are called succulent plants.
Succulents are a kind of xerophytes. An example of this is Cacti. Such plants retain and store water inside the fleshy tissues of plants, to be used later. Several succulents have disconnected the dark and light reactions of photosynthesis in a way that can keep their stomata closed in the daytime and during the night, open consuming carbon dioxide forming organic acids, stored in the vacuoles of cells.
Figure : Succulents