Step-by-step explanation:
In your search for the desert-adapted plant on the uninhabited island at approximately 40° south latitude in the middle of the Pacific Ocean, it's most likely to be found on the western half of the island. This is because as you move closer to the equator from higher latitudes, you tend to encounter warmer and drier climates, which are more conducive to desert-adapted vegetation. Additionally, the description of menacing volcanoes in the eastern half suggests that this area may have harsher conditions less suitable for desert flora, making the western half the more promising location for your research.