Complex sentence: Past expeditions collected seeds from "A. brownii", but no plants have managed to survive using ex-situ conservation efforts outside of its native habitat, and there are currently no known plants or seeds in any botanical gardens.
Split into simpler sentences: Past expeditions collected seeds from "A. brownii", but no plants have managed to survive using ex-situ conservation efforts outside of its native habitat. There are currently no known plants or seeds from "A. brownii" in any botanical gardens.