Based on the Oblivion quest, "Seeking your Roots". This mod adds a number of non-respawning, lore-friendly "Nirnroot" plants to Morrowind. In a questline with multiple stages you will meet Erlandil, an Altmer-Alchemist from Summerset Isle and help him collecting those rare plants. The quest starts naturally as you play (by picking-up a Nirnroot) and continues reliable and solid, without bugs or illogical tasks. I believe the final reward is something to look forward to and to keep you motivated for this rather long quest, which you will probably have in your journal for a while.