Never get turned around in the Mojave Desert again. As long as you can find this plant, it will point you south!
Directionality is seen in many cactus species, with our barrel cactus (Ferocactus cylindraceus) serving as a good example.
The succulent stems of these cacti lean toward the south, maximizing solar radiation on the growing tip and reproductive area of the cactus, and minimizing radiation to the sides of the stem.
The Mojave Kingcup Cactus (Echinocereus triglochidiatus ssp. mojavensis), among others, will also point you south!