Stuck in main storyline - find plant for Katu

I know there was a thread about this on the Deep Shadows forum saying that the plant was in the Oasis near the village, but I've searched in the three nearby Oasis's and can't find it. Could someone tell me it's exact location? Does the plant show up before you start the quest? I'm worried that I came across it doing a side quest and lost it if it's even possible to lose quest items.