Althea and Garan's first goal, the legendary Elyssian Stone, was said to be—if it existed—in the desert area. Specifically, where the Undead resided.
Since they were heading to a place teeming with them, they might as well finish a mission as well. Further, they could also find out more about who set such a mission, and perhaps they had more information about what had been going on in there.
Of course, there could be anonymity in the missions, but since they were delivering items, they could find clues.
The plant, the igneus flower, was something Althea was familiar with thanks to Dune Town.
It had already been an established fact that many subsidiaries, allies, and even guests would continuously bring any plant they could that was not endemic around Alterra. This was one of the first desert plants that reached Alterra.
