if it's going from the widest range (from being common) to the narrowest range ( to being more specific), the species is found at last, and the one above it is its genus.
one mnemonic to remember this is:
Kids Prefer Candies Over Fresh Green Salads.
Kingdom Phylum Class Order Family Genus Species. ( from highest rank to lowest).
i hope this helps you to better understand things,
I would love to answer this question for you, sadly you have not provided us with the diagram. So I am not able to see which type of plant experienced a drought.
