Go ahead and drop your most disappointing failure-to-drop-sap (or ether event mcguffin-resouce) after a kill.
Shade Mother in Western Skyrim did not drop sap for me. She's a hag raven. Feels kinda naturey to me. And she even glows green. Dry old crone! LOL
Side note, this thread is not for advice on the most efficient way to get sap. Or to repeat the quest text. I'm not interested in being efficient in my recreational activities. And I know what the quest text says. I have gotten fat and light skins from all kinds of creatures not listed. 🍻